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OpenGL Rendering Quake III BSP In DirectX

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Hey, I've been reading a load of documentation lately on Quake III's BSP format as well as a number of tutorials, namely the one's from GameTutorials.com in which the writer goes through loading the base level to lightmaps and utilizing nodes and leaves. The one question that is nagging at the back of my mind is how to go about rendering the level face by face. I know in OpenGL there is no such think as a "vertex buffer" and thus they can use glDrawArrays quite easily without a decline in performance. In DirectX on the other hand I know of no way of drawing a number of texture mapped primitives without having a vertex buffer with at least 3 vertices assigned to it. I think what I'm looking at here is having to use a dynamic vertex buffer and as I loop through each "face" from the BSP file, I populate the vertex buffer, set the textures (normal and lightmap), set any lights and then render it, continually looping through each face until I reach the end. From looking at this I believe this should stop the video card from locking during rendering as it will be rendering a group of vertices while I'm buidling up the next face. for( int i = 0; i < numFaces; i++ ) { lock the buffer populate the buffer with faces[ i ]; set the texture at texture[ faces->texturID ]; set the stream source and everything drawprimitive } If anyone else has any other experience with this it'd be great if you could provide me with some insight of whether or not this is how you went about rendering the level, and if not, what is the best solution here? Thanks in advance, Permafried-

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The method you propose is *definetly* not DirectX friendly. Locking the vertex buffer and calling DrawPrimitive() for each face is going to kill your application.

According to this slideset (which I consider reliable), you only get about 25,000 DrawPrimitive() calls per second. You could very easily go over 25,000 DrawPrimitive() calls per frame.

Also, you shouldn't be locking many vertex buffer per frame. Locking a vertex buffer or index buffer causes a windows mode transition, from user mode to kernel mode (and back). This is to be avoided, or at least kept to a minimum.

I'm not familiar with Quake III BSP, but would it be possible to put all of the visible triangles into a vertex buffer, and make one DP call? Like:
Lock the buffer

for each rendered face
{
add vertices
}

Unlock the vertex buffer

Set texture
Set stream source
DrawPrimitive


However, you probably have a lot of different textures visible at one time. If possible, minimize the number of textures, because each requires another SetTexture() and DrawPrimitive(). You could still only make one Lock(), if you do it like this:
Lock the buffer

for each texture n
{
for each rendered face with texture n
{
add vertices
}

add vertex offset to offsetList
}

Unlock the buffer

for each offset in offsetList
{
setTexture
SetStreamSource with offset
DrawPrimitive
}

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Circlesoft,

Thanks for the reply. I know that rendering my level in this way is definitely not DirectX friendly but the problem arises, as you mentioned, having multiple textures where each face has not only a graphical texture assigned to it but a lightmap as well. This means that for each x number of vertices, I need to render just that subset and the texture assigned to it. This is where loading in and utilizing the Quake III .BSP format's PVS data will come in handy.

A thorough explanation of Quake III .BSP formats can be found at:
Game Tutorials

There are also 3 tutorials which build upon one another from loading and rendering the raw vertices to implementing the BSP tree and PVS.

I'm still going to be using a dynamic vertex buffer and populating it every frame with the PVS (I guess I could do a check and if it hasn't changed, don't update it ^_^) but looping through in this way should hopefully help to improve my performance.

Thanks again, I'll keep your suggestions in mind when I go back to optimizing this evening. My first goal is to simply get the level rendering in which case the architecture mentioned above should easily port over from raw rendering to selective rendering. Let me know if this seems to make a little more sense and I'm on the right track based on what you suggested.

Permafried-

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I have been working on a Quake 3 renderer lately and Dustin is correct. You need to sort the faces by texture and then add them to the vertex/index buffer. Make sure when you create your vertex and index buffers that you use the dynamic creation flag and also when you lock them you want to use the discard flag.

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Yzzid,

I was wondering if you'd had any success to this point getting your level to render correctly or not. I know that Quake III uses triangle fans to render, but my biggest problem right now is figuring out the number of primitives to render based on the number of vertices contained within the face.

I created a normal vertex buffer for the sake of attempting to render the entire thing, but no matter what I've tried I can't get the thing to display, though I'm almost 100% sure it's loading correctly as I've gotten all the required information including vertices, faces and textures to this point.

When I load the level I've populated the vertex buffer and loaded all of the textures and have tried looping through the faces and rendeirng them using:


pd3dDevice->SetFVF( CLevel::dwFVF );
pd3dDevice->SetStreamSource( 0, m_pvbVertexLevelVertexBuffer, 0, sizeof( CLevelVertex ) );
pd3dDevice->SetTexture( 0, m_pFaces[ i ]->textureID );
DrawPrimitive( D3DPT_TRIANGLEFAN, m_pFaces[ i ]->startVertex, ?!? );




For the time being, I really shouldn't have to worry about the offset into my vertex buffer as each face cotains the offset into the BSPVertex array which would correspond to the vertex buffer's offset as i copy vertex by vertex. Any help here would be appreciated as I'm a little confused oh why this thing just won't render.

Thanks again,

Permafried-

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That seems to be the correct method.
I would also add that you should be using an index buffer and use the indices for each face too.
What you are doing should, in theory, work.
Try putting using the debug DirectX library on the highest output level and your output window in Visual Studio should give you some clues as to what the problem is.

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I think one of the major problems is rendering using triangle fans as Quake III did, but DirectX has the limitation that you have to provide any drawing method with the number of primitives, and there is no nice way as far as I can see to calculate the number of triangle fans based on the number of vertices to be drawn. I have a feeling if I could resolve this number correctly and mess with my rendering a little bit more I should be on the right track.

Any ideas on this?

Another thing I found, which is incredibly strange....I dumped out the vertices as they were loaded from my application and the last 15 vertices are churning out absolute garbage. I compared this with the dump from the OpenGL tutorial I've been using as a guide and my code looks identical as far as I can tell. I am getting back the correct number of vertices, faces and textures, but my vertices aren't loading correctly after the 52nd one. Here's what I've got as far as loading vertices:


struct tBSPVertex
{
D3DXVECTOR3 d3dvOrigin; ///< The position of the vertex in 3D space
D3DXVECTOR2 d3dvTexCoords; ///< The texture coordinates of this vertex's texture
D3DXVECTOR2 d3dvTexLightMap; ///< The texture coordinates of this vertex's lightmap
D3DXVECTOR3 d3dvNormal; ///< The normal calculated for this vertex
unsigned char ucColour[ 4 ]; ///< The colour of this vertex
};

bool CLevel::levelLoadLevel( char* szLevel )
{
// get the total number of vertices
m_iNumOfVertices = bspLumps[ LUMP_VERTICES ].iLength / sizeof( tBSPVertex );

// allocate memory for the vertices to be read in
m_pVertices = new tBSPVertex[ m_iNumOfVertices ];

// seek to the position in the file which contains the vertices
fseek( pFile, bspLumps[ LUMP_VERTICES ].iOffset, SEEK_SET );

// loop through all the vertices and populate the vertex array
for( int i = 0; i < m_iNumOfVertices; i++ )
{
// read in the current vertex
fread( &m_pVertices[ i ], 1, sizeof( tBSPVertex ), pFile );

// reverse the positional coords, quake III uses Z as up
float fTemp = m_pVertices[ i ].d3dvOrigin.y;
m_pVertices[ i ].d3dvOrigin.y = m_pVertices[ i ].d3dvOrigin.z;
m_pVertices[ i ].d3dvOrigin.z = -fTemp;

// negate the textures coords otherwise it'll be upside down
m_pVertices[ i ].d3dvTexCoords.y *= -1;
}




I've also tried without swapping the y and z and I can manage to get to vertex 70 before it barfs..I'm totally lost on this one, I can see nothing wrong with my code above nor the level load itself....hopefully a fresh set of eyes will help ^_^.

Thanks again for all your help,

Permafried-

[Edited by - Permafried- on August 17, 2004 9:28:31 PM]

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What flags are you opening your file with? I recently had a problem just like this. The solution was to open it read-binary flag:

file = fopen( filename, "rb" );

Also, you may just want to try something to see if it makes a difference:

fseek( pFile, bspLumps[ LUMP_VERTICES ].iOffset, SEEK_SET );
fread( (void*)m_pVertices, m_iNumOfVertices, sizeof( tBSPVertex ), pFile );

// loop through all the vertices and populate the vertex array
for( int i = 0; i < m_iNumOfVertices; i++ )
{
// reverse the positional coords, quake III uses Z as up
float fTemp = m_pVertices[ i ].d3dvOrigin.y;
m_pVertices[ i ].d3dvOrigin.y = m_pVertices[ i ].d3dvOrigin.z;
m_pVertices[ i ].d3dvOrigin.z = -fTemp;

// negate the textures coords otherwise it'll be upside down
m_pVertices[ i ].d3dvTexCoords.y *= -1;
}

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Hey,

I can't believe after all that trouble of disappearing vertices when loading that it was that simple little b....and of course while going through line after line of code that is something more than easy enough to miss.

Thanks a lot that solved the problem, I now have all the vertices in the exact order and format that the tutorial does, so hopefully tomorrow I can tackle the issue of rendering.

In regards to rendering, if I'm not mistaken the number of primitives on a DrawPrimitive call when using triangle fans should be ( number of vertices - 2 ), this seems to stay true in all cases even though I haven't tried it in code yet.

Thanks again,

Permafried-

[Edited by - Permafried- on August 18, 2004 11:47:52 AM]

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Hello again,

Well I finally got the geometry rendering, but noticed my textures were completely whack. I created a quick file output routine to check all the information about the vertex and noticed the texture coords are right outta whack (ignore the - this is due to a dumb calculation I had in the code):

Face: 0
Start Vert: 0
Num Verts: 6
Vertex 0: -128 264 64 0 -4
Vertex 1: -128 264 -64 0 -2
Vertex 2: 0 264 -184 2 -0.125
Vertex 3: 184 264 -184 4.875 -0.125
Vertex 4: 184 264 184 4.875 -5.875
Vertex 5: -128 264 184 0 -5.875
Texture: 0

Face: 1
Start Vert: 6
Num Verts: 5
Vertex 6: -128 264 184 2 -5.875
Vertex 7: 184 264 184 6.875 -5.875
Vertex 8: 184 632 184 6.875 -0.125
Vertex 9: -248 632 184 0.125 -0.125
Vertex 10: -248 384 184 0.125 -4
Texture: 0

Face: 2
Start Vert: 11
Num Verts: 4
Vertex 11: 184 264 184 0.125 -5.875
Vertex 12: 184 264 -184 5.875 -5.875
Vertex 13: 184 632 -184 5.875 -0.125
Vertex 14: 184 632 184 0.125 -0.125
Texture: 0

Face: 3
Start Vert: 15
Num Verts: 5
Vertex 15: -248 632 -184 0.125 -0.125
Vertex 16: 184 632 -184 6.875 -0.125
Vertex 17: 184 264 -184 6.875 -5.875
Vertex 18: 0 264 -184 4 -5.875
Vertex 19: -248 320 -184 0.125 -5
Texture: 0

Face: 4
Start Vert: 20
Num Verts: 5
Vertex 20: -248 632 184 0.125 -0.125
Vertex 21: -248 632 -184 5.875 -0.125
Vertex 22: -248 320 -184 5.875 -5
Vertex 23: -248 320 -64 4 -5
Vertex 24: -248 384 184 0.125 -4
Texture: 0

Face: 5
Start Vert: 25
Num Verts: 4
Vertex 25: -248 632 184 0.125 -5.875
Vertex 26: 184 632 184 6.875 -5.875
Vertex 27: 184 632 -184 6.875 -0.125
Vertex 28: -248 632 -184 0.125 -0.125
Texture: 0

Face: 6
Start Vert: 29
Num Verts: 4
Vertex 29: -128 384 64 0.5 0
Vertex 30: -128 320 -64 1.5 -0.5
Vertex 31: -128 264 -64 1.5 -0.9375
Vertex 32: -128 264 64 0.5 -0.9375
Texture: 1

Face: 7
Start Vert: 33
Num Verts: 4
Vertex 33: -248 384 64 0.0625 -1.5
Vertex 34: -248 320 -64 0.0625 -0.5
Vertex 35: -128 320 -64 1 -0.5
Vertex 36: -128 384 64 1 -1.5
Texture: 1

Face: 8
Start Vert: 37
Num Verts: 4
Vertex 37: -128 320 -64 1 -1.5
Vertex 38: -248 320 -64 0.0625 -1.5
Vertex 39: -248 320 -184 0.0625 -0.5625
Vertex 40: -128 320 -184 1 -0.5625
Texture: 1

Face: 9
Start Vert: 41
Num Verts: 4
Vertex 41: 0 264 -184 1.4375 -0.9375
Vertex 42: 0 264 -64 0.5 -0.9375
Vertex 43: 0 272 -64 0.5 -0.875
Vertex 44: 0 272 -184 1.4375 -0.875
Texture: 1

Face: 10
Start Vert: 45
Num Verts: 4
Vertex 45: 0 264 -64 1 -0.9375
Vertex 46: -128 264 -64 0 -0.9375
Vertex 47: -128 320 -64 0 -0.5
Vertex 48: 0 272 -64 1 -0.875
Texture: 1

Face: 11
Start Vert: 49
Num Verts: 4
Vertex 49: -128 320 -184 0 -0.5625
Vertex 50: 0 272 -184 1 -0.5625
Vertex 51: 0 272 -64 1 -1.5
Vertex 52: -128 320 -64 0 -1.5
Texture: 1

Face: 12
Start Vert: 53
Num Verts: 4
Vertex 53: -128 264 64 1.5 -0.9375
Vertex 54: -128 264 184 0.5625 -0.9375
Vertex 55: -128 384 184 0.5625 0
Vertex 56: -128 384 64 1.5 0
Texture: 1

Face: 13
Start Vert: 57
Num Verts: 4
Vertex 57: -128 384 184 1 -1.4375
Vertex 58: -248 384 184 0.0625 -1.4375
Vertex 59: -248 384 64 0.0625 -0.5
Vertex 60: -128 384 64 1 -0.5
Texture: 1

Face: 14
Start Vert: 61
Num Verts: 4
Vertex 61: 40 320 184 0.5625 -0.5
Vertex 62: 40 320 88 1.3125 -0.5
Vertex 63: 40 336 88 1.3125 -0.375
Vertex 64: 40 336 184 0.5625 -0.375
Texture: 1

Face: 15
Start Vert: 65
Num Verts: 4
Vertex 65: 40 320 88 0.3125 -0.5
Vertex 66: 184 320 88 1.4375 -0.5
Vertex 67: 184 336 88 1.4375 -0.375
Vertex 68: 40 336 88 0.3125 -0.375
Texture: 1

Face: 16
Start Vert: 69
Num Verts: 4
Vertex 69: 184 320 88 1.4375 -0.6875
Vertex 70: 40 320 88 0.3125 -0.6875
Vertex 71: 40 320 184 0.3125 -1.4375
Vertex 72: 184 320 184 1.4375 -1.4375
Texture: 1

Face: 17
Start Vert: 73
Num Verts: 4
Vertex 73: 40 336 184 0.3125 -1.4375
Vertex 74: 40 336 88 0.3125 -0.6875
Vertex 75: 184 336 88 1.4375 -0.6875
Vertex 76: 184 336 184 1.4375 -1.4375
Texture: 1

The last two digits are the texture coordinates and I've never seen texture coords of 4.0 in my life. Is there any way to make DirectX recognize this or am I basically SOL for rendering with these kinds of numbers?

Thanks again,

Permafried-

PS: Yzzid, if you happen to come across this post again, have you ever run across this when rendering using ur Quake III BSP renderer or is something else maybe the problem here?

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Well it turns out I found my problem and have officially loaded my first fully texture mapped Quake III .BSP level in DirectX. Apparently having normals defined as part of your custom vertex but not having lighting enabled causes DX to puke when rendering textures.

Long story short, it's working and now I'm moving up to rendering full quake III levels like DM8 etc.

Thanks again for everyone's help, much appreciated. If anyone has any questions about this I'll be more than happy to help out with it and may look into turning it into a tutorial once I figure out lightmaps, brushes, etc.

Permafried-

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Glad to see you making progress.

I just finished getting most of my shader features implemented.
The only things which aren't working are environment mapping, sky boxes, deformed vertexes, and turblant textures.

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Yzzid,

Wow you're miles ahead of me....I almost jumped outta my chair when I managed to get the level rendering fully texture mapped ^_^. I managed to get lightmaps somewhat working last nite, but think I have a few problems with how I'm building up the texture based on the information provided. All I do is create a blank texture using CreateTexture, then make a call to LockRect and loop through each pixel of the pBits and assign a colour to it 1 pixel at a time.

I'm going to experiment with this a little more tonite when I get home and hopefully can manage to solve this and move onto working with leaves, nodes and the PVS.

Permafried-

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You must realize that I have been working on this for a few years.

It has taken me a while to understand everything.

One thing that has help immensely is that there is a rendering engine in the ShaderX book. That is what I am using as a reference right now. I highly recommend picking it up.

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I may have to look into getting a copy of that....I'm developing based on documentation on the Quake III BSP format from what is available online, and pieceing the rest of it together based on what I know about OpenGL, DirectX and C++ in general. For only working on the code for 4 days now or so I'm happy with the results, but I have a tight timeline as it's a school project.

It's supposed to run from September to December, but since I had the summer off as a co-op term I decided to work on it all summer instead, just so I can build the type of project I'm able to add to my portfolio after school, not this piece of junk threw it together as fast as possible just to get the mark ^_^.

If I run into anymore problems I'll keep adding to this thread, particularly since it may be of use to others in the community if they're interested in creating their own BSP parser/rendering engine. It still blows my mind that my texture coordinates are correct, even though the values that were output to the file are totally out of whack and shouldn't have worked in the first place, makes me wonder if they're in binary format, and if I were to convert them over to ASCII via conversion methods if I'd see the real values or not.

Permafried-

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Texture coordinates can be outside of the range of 0.0 to 1.0. If this is the case then the texture just repeats if the addressing mode is set to wrapping.

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Hey,

Well I thought I had it down, but I seem to have problems with the creation of some of my lightmaps. It worked fine in a simple level which consisted of a cube with a ramp and a wooden platform, but now loading a larger level, I get a nice whack of purple in places and I'm not too sure why. I thought the code to create the lightmaps was working well....but maybe someone can spot an error:


for( int i = 0; i < m_pLevel->levelGetNumberOfLightmaps(); i++ )
{
// create the texture at index i, we'll make this
// dynamic so we can clear it out and re-write later
D3DXCreateTexture( DXUTGetD3DDevice(), 128, 128, D3DX_DEFAULT, 0,
D3DFMT_X8R8G8B8, D3DPOOL_MANAGED,
&m_pLightmaps[ i ].m_d3dtTexture );

// get the lightmap's surface descriptor
m_pLightmaps[ i ].m_d3dtTexture->GetSurfaceLevel( 0, &pLightmapSurface );

// lock the texture's entire surface, this gets us
// ready to begin writing out the pixel information
pLightmapSurface->LockRect( &rect, NULL, 0 );

// get the surface information in bit form, this will
// allow us to write out the information pixel by pixel
pTextureSurface = static_cast<unsigned char*>( rect.pBits );
dwBitsPerRow = rect.Pitch;

// loop through all items in each row, Quake III
// stores this information in 128 pixels
for( int x = 0; x < 128; x++ )
{
// get the current index into the surface
DWORD dwIndex = x * dwBitsPerRow;

// loop through all items in each column, Quake III
// stores this information in 128 pixels as well
for( int y = 0; y < 128; y++ )
{
// get the RGB elements out of the array, we need
// to adjust the gamma so they're a little brighter
float fRed = static_cast<float>( m_pLevel->levelGetLightmapAtIndex( i )->ucImageBits[ x ][ y ][ 2 ] );
float fGreen = static_cast<float>( m_pLevel->levelGetLightmapAtIndex( i )->ucImageBits[ x ][ y ][ 1 ] );
float fBlue = static_cast<float>( m_pLevel->levelGetLightmapAtIndex( i )->ucImageBits[ x ][ y ][ 0 ] );
float fScale = 1.0f;

// we'll brighten them up by a factor of 10, this will
// still give a nice effect without blowing the user's eyes
fRed = fRed * ( 10 / 255.0f );
fGreen = fGreen * ( 10 / 255.0f );
fBlue = fBlue * ( 10 / 255.0f );

// check if the red went past the highest value
if( fRed > 1.0f && ( ( 1.0f / fRed ) < 1.0f ) )
{
// set the new scale
fScale = ( 1.0f / fRed );
}

// check if the green went past the highest value
if( fGreen > 1.0f && ( ( 1.0f / fGreen ) < 1.0f ) )
{
// set the new scale
fScale = ( 1.0f / fGreen );
}

// check if the blue went past the highest value
if( fBlue > 1.0f && ( ( 1.0f / fBlue ) < 1.0f ) )
{
// set the new scale
fScale = ( 1.0f / fBlue );
}

// get the scale for this pixel
fScale *= 255.0f;

// multiply all our pixel values by this scale
// this will keep them constant but brighten them
fRed *= fScale;
fGreen *= fScale;
fBlue *= fScale;

// setup the alpha information for all four bytes
pTextureSurface[ dwIndex + y * 4 + 0 ] = static_cast<unsigned char>( fRed );
pTextureSurface[ dwIndex + y * 4 + 1 ] = static_cast<unsigned char>( fGreen );
pTextureSurface[ dwIndex + y * 4 + 2 ] = static_cast<unsigned char>( fBlue );
pTextureSurface[ dwIndex + y * 4 + 3 ] = 255;
}
}



I'm going to continue investigating the problem in case this isn't it, but I can't really seem to find anywhere else where the problem might be arising from.

Permafried-

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Guest Anonymous Poster
Your brightening method seems somewhat bizarre .. try using a power curve if you really need gamma correction. Also Q3 uses a gamma ramp where 0-128 is a linear or power ramp and 128-255 just is max, to be able to have intermediate blending results above 1.

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Hey,

Thanks for the reply, I tried commenting out the code which handles gamma correction, and sure enough the ugly purple blotches disappeared so this seems to be the root of the problem. My ultimate goal would be to do this in hardware rather than through this algorithm but I'm still searching on how to accomplish this.

Anyone have any ideas on this, and if not, would anyone know of any good links explaning different means of apply gamma correction?

Thanks again everyone,

Permafried-

[Edited by - Permafried- on August 22, 2004 2:14:03 PM]

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Hey hey, I am curious about what you have done, is there a way for you to write a follow up article or perhaps post what you have made ?? I am learning a lot of this stuff too trying to make sense of it all !

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A gamma ramp is the way to go so you don't have to do all this yourself, however, if you want this to run in a window, you can't use the gamma functions (they only work in fullscreen mode IIRC).

You can see a screenshot of my viewer here

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Don't render the faces as triangle fans, maps compiled with later bsp-compilers don't use triangle fans and you will get som pretty ugly results. Most web pages describing the format got this wrong.

Instead render as triangles with struct face.vertex as the start of the list of vertices and the meshverts starting at struct face.meshvert through struct face.n_meshverts as indices starting from struct face.vertex.

That might sound confusing, basically just take the meshvert indices of the face and index the list of vertices starting at the particular index given in the face by the vertex member.

This works with old and new maps without any problems and it's also the way to render type 3 faces (models) so if you get this down you'll be able to see all the models as well.

Good luck!

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Fiskbil,

I think I've finally run into the issue you were talking about in regards to triangle fans. All I got was a whack of geometry all over hell's half acre with textures mapped here and there. I'd have to say it gave me my laugh for the day....but now I'm confused on how to implement what you mentioned in your last post.

Does this mean I require an index buffer as well as my vertex buffer...and I populate the index buffer with the mesh indices...or do I want to call DrawPrimitive() in a loop using the meshes? Everything I've tried up to this point has ended up in my world being warped beyond belief with holes, missing textures and tears all over the place.....and I can't seem to exactly figure out what you're describing in code from your explanation.

Thanks,

Permafried-

[Edited by - Permafried- on September 9, 2004 4:47:13 PM]

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OK first you need to create an index buffer to go with the vertex buffer.

Then for each face you do the following:

1. Fill the vertex buffer with the vertices using the first vertex and number of vertices members of the face struct.
2. Fill the index buffer with the indices using the first index and number of indices members of the face struct.
3. Call SetStreamSource passing in your vertex buffer
4. Call SetIndices passing in your index buffer
5. Set your FVF to match your vertex format
3. Call DrawIndexedPrimitive passing in triangle list for the type and numindices/3 for the number of primitives.

This should get you started in the right direction although it doesn't work for bezier patches as they do not have indices. You have to actually do the math on them to calculate all the vertices and indices. Right now stick with rendering just the polys and meshes as they have indices included with them.

Good luck.
Let us know how you make out.

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Yzzid,

Good to hear from you again...and thanks for the much clearer explanation. I thought maybe I'd gotten away without having to use dynamic vertex and index buffers while rendering but apparently I'm right back to square one again. I'm assuming since I'll be rendering one face while preparing for the next that my framerate shouldn't suffer too too much though I'm trying to keep in mind what Circlesoft mentioned way back when this thread first started.

Thanks again and I'll let you know how it goes.

Permafried-

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      Hi guys, im having a little problem fixing a bug in my program since i multi-threaded it. The app is a little video converter i wrote for fun. To help you understand the problem, ill first explain how the program is made. Im using Delphi to do the GUI/Windows part of the code, then im loading a c++ dll for the video conversion. The problem is not related to the video conversion, but with OpenGL only. The code work like this:

       
      DWORD WINAPI JobThread(void *params) { for each files { ... _ConvertVideo(input_name, output_name); } } void EXP_FUNC _ConvertVideo(char *input_fname, char *output_fname) { // Note that im re-initializing and cleaning up OpenGL each time this function is called... CGLEngine GLEngine; ... // Initialize OpenGL GLEngine.Initialize(render_wnd); GLEngine.CreateTexture(dst_width, dst_height, 4); // decode the video and render the frames... for each frames { ... GLEngine.UpdateTexture(pY, pU, pV); GLEngine.Render(); } cleanup: GLEngine.DeleteTexture(); GLEngine.Shutdown(); // video cleanup code... }  
      With a single thread, everything work fine. The problem arise when im starting the thread for a second time, nothing get rendered, but the encoding work fine. For example, if i start the thread with 3 files to process, all of them render fine, but if i start the thread again (with the same batch of files or not...), OpenGL fail to render anything.
      Im pretty sure it has something to do with the rendering context (or maybe the window DC?). Here a snippet of my OpenGL class:
      bool CGLEngine::Initialize(HWND hWnd) { hDC = GetDC(hWnd); if(!SetupPixelFormatDescriptor(hDC)){ ReleaseDC(hWnd, hDC); return false; } hRC = wglCreateContext(hDC); wglMakeCurrent(hDC, hRC); // more code ... return true; } void CGLEngine::Shutdown() { // some code... if(hRC){wglDeleteContext(hRC);} if(hDC){ReleaseDC(hWnd, hDC);} hDC = hRC = NULL; }  
      The full source code is available here. The most relevant files are:
      -OpenGL class (header / source)
      -Main code (header / source)
       
      Thx in advance if anyone can help me.
    • By DiligentDev
      This article uses material originally posted on Diligent Graphics web site.
      Introduction
      Graphics APIs have come a long way from small set of basic commands allowing limited control of configurable stages of early 3D accelerators to very low-level programming interfaces exposing almost every aspect of the underlying graphics hardware. Next-generation APIs, Direct3D12 by Microsoft and Vulkan by Khronos are relatively new and have only started getting widespread adoption and support from hardware vendors, while Direct3D11 and OpenGL are still considered industry standard. New APIs can provide substantial performance and functional improvements, but may not be supported by older hardware. An application targeting wide range of platforms needs to support Direct3D11 and OpenGL. New APIs will not give any advantage when used with old paradigms. It is totally possible to add Direct3D12 support to an existing renderer by implementing Direct3D11 interface through Direct3D12, but this will give zero benefits. Instead, new approaches and rendering architectures that leverage flexibility provided by the next-generation APIs are expected to be developed.
      There are at least four APIs (Direct3D11, Direct3D12, OpenGL/GLES, Vulkan, plus Apple's Metal for iOS and osX platforms) that a cross-platform 3D application may need to support. Writing separate code paths for all APIs is clearly not an option for any real-world application and the need for a cross-platform graphics abstraction layer is evident. The following is the list of requirements that I believe such layer needs to satisfy:
      Lightweight abstractions: the API should be as close to the underlying native APIs as possible to allow an application leverage all available low-level functionality. In many cases this requirement is difficult to achieve because specific features exposed by different APIs may vary considerably. Low performance overhead: the abstraction layer needs to be efficient from performance point of view. If it introduces considerable amount of overhead, there is no point in using it. Convenience: the API needs to be convenient to use. It needs to assist developers in achieving their goals not limiting their control of the graphics hardware. Multithreading: ability to efficiently parallelize work is in the core of Direct3D12 and Vulkan and one of the main selling points of the new APIs. Support for multithreading in a cross-platform layer is a must. Extensibility: no matter how well the API is designed, it still introduces some level of abstraction. In some cases the most efficient way to implement certain functionality is to directly use native API. The abstraction layer needs to provide seamless interoperability with the underlying native APIs to provide a way for the app to add features that may be missing. Diligent Engine is designed to solve these problems. Its main goal is to take advantages of the next-generation APIs such as Direct3D12 and Vulkan, but at the same time provide support for older platforms via Direct3D11, OpenGL and OpenGLES. Diligent Engine exposes common C++ front-end for all supported platforms and provides interoperability with underlying native APIs. It also supports integration with Unity and is designed to be used as graphics subsystem in a standalone game engine, Unity native plugin or any other 3D application. Full source code is available for download at GitHub and is free to use.
      Overview
      Diligent Engine API takes some features from Direct3D11 and Direct3D12 as well as introduces new concepts to hide certain platform-specific details and make the system easy to use. It contains the following main components:
      Render device (IRenderDevice  interface) is responsible for creating all other objects (textures, buffers, shaders, pipeline states, etc.).
      Device context (IDeviceContext interface) is the main interface for recording rendering commands. Similar to Direct3D11, there are immediate context and deferred contexts (which in Direct3D11 implementation map directly to the corresponding context types). Immediate context combines command queue and command list recording functionality. It records commands and submits the command list for execution when it contains sufficient number of commands. Deferred contexts are designed to only record command lists that can be submitted for execution through the immediate context.
      An alternative way to design the API would be to expose command queue and command lists directly. This approach however does not map well to Direct3D11 and OpenGL. Besides, some functionality (such as dynamic descriptor allocation) can be much more efficiently implemented when it is known that a command list is recorded by a certain deferred context from some thread.
      The approach taken in the engine does not limit scalability as the application is expected to create one deferred context per thread, and internally every deferred context records a command list in lock-free fashion. At the same time this approach maps well to older APIs.
      In current implementation, only one immediate context that uses default graphics command queue is created. To support multiple GPUs or multiple command queue types (compute, copy, etc.), it is natural to have one immediate contexts per queue. Cross-context synchronization utilities will be necessary.
      Swap Chain (ISwapChain interface). Swap chain interface represents a chain of back buffers and is responsible for showing the final rendered image on the screen.
      Render device, device contexts and swap chain are created during the engine initialization.
      Resources (ITexture and IBuffer interfaces). There are two types of resources - textures and buffers. There are many different texture types (2D textures, 3D textures, texture array, cubmepas, etc.) that can all be represented by ITexture interface.
      Resources Views (ITextureView and IBufferView interfaces). While textures and buffers are mere data containers, texture views and buffer views describe how the data should be interpreted. For instance, a 2D texture can be used as a render target for rendering commands or as a shader resource.
      Pipeline State (IPipelineState interface). GPU pipeline contains many configurable stages (depth-stencil, rasterizer and blend states, different shader stage, etc.). Direct3D11 uses coarse-grain objects to set all stage parameters at once (for instance, a rasterizer object encompasses all rasterizer attributes), while OpenGL contains myriad functions to fine-grain control every individual attribute of every stage. Both methods do not map very well to modern graphics hardware that combines all states into one monolithic state under the hood. Direct3D12 directly exposes pipeline state object in the API, and Diligent Engine uses the same approach.
      Shader Resource Binding (IShaderResourceBinding interface). Shaders are programs that run on the GPU. Shaders may access various resources (textures and buffers), and setting correspondence between shader variables and actual resources is called resource binding. Resource binding implementation varies considerably between different API. Diligent Engine introduces a new object called shader resource binding that encompasses all resources needed by all shaders in a certain pipeline state.
      API Basics
      Creating Resources
      Device resources are created by the render device. The two main resource types are buffers, which represent linear memory, and textures, which use memory layouts optimized for fast filtering. Graphics APIs usually have a native object that represents linear buffer. Diligent Engine uses IBuffer interface as an abstraction for a native buffer. To create a buffer, one needs to populate BufferDesc structure and call IRenderDevice::CreateBuffer() method as in the following example:
      BufferDesc BuffDesc; BufferDesc.Name = "Uniform buffer"; BuffDesc.BindFlags = BIND_UNIFORM_BUFFER; BuffDesc.Usage = USAGE_DYNAMIC; BuffDesc.uiSizeInBytes = sizeof(ShaderConstants); BuffDesc.CPUAccessFlags = CPU_ACCESS_WRITE; m_pDevice->CreateBuffer( BuffDesc, BufferData(), &m_pConstantBuffer ); While there is usually just one buffer object, different APIs use very different approaches to represent textures. For instance, in Direct3D11, there are ID3D11Texture1D, ID3D11Texture2D, and ID3D11Texture3D objects. In OpenGL, there is individual object for every texture dimension (1D, 2D, 3D, Cube), which may be a texture array, which may also be multisampled (i.e. GL_TEXTURE_2D_MULTISAMPLE_ARRAY). As a result there are nine different GL texture types that Diligent Engine may create under the hood. In Direct3D12, there is only one resource interface. Diligent Engine hides all these details in ITexture interface. There is only one  IRenderDevice::CreateTexture() method that is capable of creating all texture types. Dimension, format, array size and all other parameters are specified by the members of the TextureDesc structure:
      TextureDesc TexDesc; TexDesc.Name = "My texture 2D"; TexDesc.Type = TEXTURE_TYPE_2D; TexDesc.Width = 1024; TexDesc.Height = 1024; TexDesc.Format = TEX_FORMAT_RGBA8_UNORM; TexDesc.Usage = USAGE_DEFAULT; TexDesc.BindFlags = BIND_SHADER_RESOURCE | BIND_RENDER_TARGET | BIND_UNORDERED_ACCESS; TexDesc.Name = "Sample 2D Texture"; m_pRenderDevice->CreateTexture( TexDesc, TextureData(), &m_pTestTex ); If native API supports multithreaded resource creation, textures and buffers can be created by multiple threads simultaneously.
      Interoperability with native API provides access to the native buffer/texture objects and also allows creating Diligent Engine objects from native handles. It allows applications seamlessly integrate native API-specific code with Diligent Engine.
      Next-generation APIs allow fine level-control over how resources are allocated. Diligent Engine does not currently expose this functionality, but it can be added by implementing IResourceAllocator interface that encapsulates specifics of resource allocation and providing this interface to CreateBuffer() or CreateTexture() methods. If null is provided, default allocator should be used.
      Initializing the Pipeline State
      As it was mentioned earlier, Diligent Engine follows next-gen APIs to configure the graphics/compute pipeline. One big Pipelines State Object (PSO) encompasses all required states (all shader stages, input layout description, depth stencil, rasterizer and blend state descriptions etc.). This approach maps directly to Direct3D12/Vulkan, but is also beneficial for older APIs as it eliminates pipeline misconfiguration errors. With many individual calls tweaking various GPU pipeline settings it is very easy to forget to set one of the states or assume the stage is already properly configured when in fact it is not. Using pipeline state object helps avoid these problems as all stages are configured at once.
      Creating Shaders
      While in earlier APIs shaders were bound separately, in the next-generation APIs as well as in Diligent Engine shaders are part of the pipeline state object. The biggest challenge when authoring shaders is that Direct3D and OpenGL/Vulkan use different shader languages (while Apple uses yet another language in their Metal API). Maintaining two versions of every shader is not an option for real applications and Diligent Engine implements shader source code converter that allows shaders authored in HLSL to be translated to GLSL. To create a shader, one needs to populate ShaderCreationAttribs structure. SourceLanguage member of this structure tells the system which language the shader is authored in:
      SHADER_SOURCE_LANGUAGE_DEFAULT - The shader source language matches the underlying graphics API: HLSL for Direct3D11/Direct3D12 mode, and GLSL for OpenGL and OpenGLES modes. SHADER_SOURCE_LANGUAGE_HLSL - The shader source is in HLSL. For OpenGL and OpenGLES modes, the source code will be converted to GLSL. SHADER_SOURCE_LANGUAGE_GLSL - The shader source is in GLSL. There is currently no GLSL to HLSL converter, so this value should only be used for OpenGL and OpenGLES modes. There are two ways to provide the shader source code. The first way is to use Source member. The second way is to provide a file path in FilePath member. Since the engine is entirely decoupled from the platform and the host file system is platform-dependent, the structure exposes pShaderSourceStreamFactory member that is intended to provide the engine access to the file system. If FilePath is provided, shader source factory must also be provided. If the shader source contains any #include directives, the source stream factory will also be used to load these files. The engine provides default implementation for every supported platform that should be sufficient in most cases. Custom implementation can be provided when needed.
      When sampling a texture in a shader, the texture sampler was traditionally specified as separate object that was bound to the pipeline at run time or set as part of the texture object itself. However, in most cases it is known beforehand what kind of sampler will be used in the shader. Next-generation APIs expose new type of sampler called static sampler that can be initialized directly in the pipeline state. Diligent Engine exposes this functionality: when creating a shader, textures can be assigned static samplers. If static sampler is assigned, it will always be used instead of the one initialized in the texture shader resource view. To initialize static samplers, prepare an array of StaticSamplerDesc structures and initialize StaticSamplers and NumStaticSamplers members. Static samplers are more efficient and it is highly recommended to use them whenever possible. On older APIs, static samplers are emulated via generic sampler objects.
      The following is an example of shader initialization:
      ShaderCreationAttribs Attrs; Attrs.Desc.Name = "MyPixelShader"; Attrs.FilePath = "MyShaderFile.fx"; Attrs.SearchDirectories = "shaders;shaders\\inc;"; Attrs.EntryPoint = "MyPixelShader"; Attrs.Desc.ShaderType = SHADER_TYPE_PIXEL; Attrs.SourceLanguage = SHADER_SOURCE_LANGUAGE_HLSL; BasicShaderSourceStreamFactory BasicSSSFactory(Attrs.SearchDirectories); Attrs.pShaderSourceStreamFactory = &BasicSSSFactory; ShaderVariableDesc ShaderVars[] = {     {"g_StaticTexture", SHADER_VARIABLE_TYPE_STATIC},     {"g_MutableTexture", SHADER_VARIABLE_TYPE_MUTABLE},     {"g_DynamicTexture", SHADER_VARIABLE_TYPE_DYNAMIC} }; Attrs.Desc.VariableDesc = ShaderVars; Attrs.Desc.NumVariables = _countof(ShaderVars); Attrs.Desc.DefaultVariableType = SHADER_VARIABLE_TYPE_STATIC; StaticSamplerDesc StaticSampler; StaticSampler.Desc.MinFilter = FILTER_TYPE_LINEAR; StaticSampler.Desc.MagFilter = FILTER_TYPE_LINEAR; StaticSampler.Desc.MipFilter = FILTER_TYPE_LINEAR; StaticSampler.TextureName = "g_MutableTexture"; Attrs.Desc.NumStaticSamplers = 1; Attrs.Desc.StaticSamplers = &StaticSampler; ShaderMacroHelper Macros; Macros.AddShaderMacro("USE_SHADOWS", 1); Macros.AddShaderMacro("NUM_SHADOW_SAMPLES", 4); Macros.Finalize(); Attrs.Macros = Macros; RefCntAutoPtr<IShader> pShader; m_pDevice->CreateShader( Attrs, &pShader );
      Creating the Pipeline State Object
      After all required shaders are created, the rest of the fields of the PipelineStateDesc structure provide depth-stencil, rasterizer, and blend state descriptions, the number and format of render targets, input layout format, etc. For instance, rasterizer state can be described as follows:
      PipelineStateDesc PSODesc; RasterizerStateDesc &RasterizerDesc = PSODesc.GraphicsPipeline.RasterizerDesc; RasterizerDesc.FillMode = FILL_MODE_SOLID; RasterizerDesc.CullMode = CULL_MODE_NONE; RasterizerDesc.FrontCounterClockwise = True; RasterizerDesc.ScissorEnable = True; RasterizerDesc.AntialiasedLineEnable = False; Depth-stencil and blend states are defined in a similar fashion.
      Another important thing that pipeline state object encompasses is the input layout description that defines how inputs to the vertex shader, which is the very first shader stage, should be read from the memory. Input layout may define several vertex streams that contain values of different formats and sizes:
      // Define input layout InputLayoutDesc &Layout = PSODesc.GraphicsPipeline.InputLayout; LayoutElement TextLayoutElems[] = {     LayoutElement( 0, 0, 3, VT_FLOAT32, False ),     LayoutElement( 1, 0, 4, VT_UINT8, True ),     LayoutElement( 2, 0, 2, VT_FLOAT32, False ), }; Layout.LayoutElements = TextLayoutElems; Layout.NumElements = _countof( TextLayoutElems ); Finally, pipeline state defines primitive topology type. When all required members are initialized, a pipeline state object can be created by IRenderDevice::CreatePipelineState() method:
      // Define shader and primitive topology PSODesc.GraphicsPipeline.PrimitiveTopologyType = PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE; PSODesc.GraphicsPipeline.pVS = pVertexShader; PSODesc.GraphicsPipeline.pPS = pPixelShader; PSODesc.Name = "My pipeline state"; m_pDev->CreatePipelineState(PSODesc, &m_pPSO); When PSO object is bound to the pipeline, the engine invokes all API-specific commands to set all states specified by the object. In case of Direct3D12 this maps directly to setting the D3D12 PSO object. In case of Direct3D11, this involves setting individual state objects (such as rasterizer and blend states), shaders, input layout etc. In case of OpenGL, this requires a number of fine-grain state tweaking calls. Diligent Engine keeps track of currently bound states and only calls functions to update these states that have actually changed.
      Binding Shader Resources
      Direct3D11 and OpenGL utilize fine-grain resource binding models, where an application binds individual buffers and textures to certain shader or program resource binding slots. Direct3D12 uses a very different approach, where resource descriptors are grouped into tables, and an application can bind all resources in the table at once by setting the table in the command list. Resource binding model in Diligent Engine is designed to leverage this new method. It introduces a new object called shader resource binding that encapsulates all resource bindings required for all shaders in a certain pipeline state. It also introduces the classification of shader variables based on the frequency of expected change that helps the engine group them into tables under the hood:
      Static variables (SHADER_VARIABLE_TYPE_STATIC) are variables that are expected to be set only once. They may not be changed once a resource is bound to the variable. Such variables are intended to hold global constants such as camera attributes or global light attributes constant buffers. Mutable variables (SHADER_VARIABLE_TYPE_MUTABLE) define resources that are expected to change on a per-material frequency. Examples may include diffuse textures, normal maps etc. Dynamic variables (SHADER_VARIABLE_TYPE_DYNAMIC) are expected to change frequently and randomly. Shader variable type must be specified during shader creation by populating an array of ShaderVariableDesc structures and initializing ShaderCreationAttribs::Desc::VariableDesc and ShaderCreationAttribs::Desc::NumVariables members (see example of shader creation above).
      Static variables cannot be changed once a resource is bound to the variable. They are bound directly to the shader object. For instance, a shadow map texture is not expected to change after it is created, so it can be bound directly to the shader:
      PixelShader->GetShaderVariable( "g_tex2DShadowMap" )->Set( pShadowMapSRV ); Mutable and dynamic variables are bound via a new Shader Resource Binding object (SRB) that is created by the pipeline state (IPipelineState::CreateShaderResourceBinding()):
      m_pPSO->CreateShaderResourceBinding(&m_pSRB); Note that an SRB is only compatible with the pipeline state it was created from. SRB object inherits all static bindings from shaders in the pipeline, but is not allowed to change them.
      Mutable resources can only be set once for every instance of a shader resource binding. Such resources are intended to define specific material properties. For instance, a diffuse texture for a specific material is not expected to change once the material is defined and can be set right after the SRB object has been created:
      m_pSRB->GetVariable(SHADER_TYPE_PIXEL, "tex2DDiffuse")->Set(pDiffuseTexSRV); In some cases it is necessary to bind a new resource to a variable every time a draw command is invoked. Such variables should be labeled as dynamic, which will allow setting them multiple times through the same SRB object:
      m_pSRB->GetVariable(SHADER_TYPE_VERTEX, "cbRandomAttribs")->Set(pRandomAttrsCB); Under the hood, the engine pre-allocates descriptor tables for static and mutable resources when an SRB objcet is created. Space for dynamic resources is dynamically allocated at run time. Static and mutable resources are thus more efficient and should be used whenever possible.
      As you can see, Diligent Engine does not expose low-level details of how resources are bound to shader variables. One reason for this is that these details are very different for various APIs. The other reason is that using low-level binding methods is extremely error-prone: it is very easy to forget to bind some resource, or bind incorrect resource such as bind a buffer to the variable that is in fact a texture, especially during shader development when everything changes fast. Diligent Engine instead relies on shader reflection system to automatically query the list of all shader variables. Grouping variables based on three types mentioned above allows the engine to create optimized layout and take heavy lifting of matching resources to API-specific resource location, register or descriptor in the table.
      This post gives more details about the resource binding model in Diligent Engine.
      Setting the Pipeline State and Committing Shader Resources
      Before any draw or compute command can be invoked, the pipeline state needs to be bound to the context:
      m_pContext->SetPipelineState(m_pPSO); Under the hood, the engine sets the internal PSO object in the command list or calls all the required native API functions to properly configure all pipeline stages.
      The next step is to bind all required shader resources to the GPU pipeline, which is accomplished by IDeviceContext::CommitShaderResources() method:
      m_pContext->CommitShaderResources(m_pSRB, COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES); The method takes a pointer to the shader resource binding object and makes all resources the object holds available for the shaders. In the case of D3D12, this only requires setting appropriate descriptor tables in the command list. For older APIs, this typically requires setting all resources individually.
      Next-generation APIs require the application to track the state of every resource and explicitly inform the system about all state transitions. For instance, if a texture was used as render target before, while the next draw command is going to use it as shader resource, a transition barrier needs to be executed. Diligent Engine does the heavy lifting of state tracking.  When CommitShaderResources() method is called with COMMIT_SHADER_RESOURCES_FLAG_TRANSITION_RESOURCES flag, the engine commits and transitions resources to correct states at the same time. Note that transitioning resources does introduce some overhead. The engine tracks state of every resource and it will not issue the barrier if the state is already correct. But checking resource state is an overhead that can sometimes be avoided. The engine provides IDeviceContext::TransitionShaderResources() method that only transitions resources:
      m_pContext->TransitionShaderResources(m_pPSO, m_pSRB); In some scenarios it is more efficient to transition resources once and then only commit them.
      Invoking Draw Command
      The final step is to set states that are not part of the PSO, such as render targets, vertex and index buffers. Diligent Engine uses Direct3D11-syle API that is translated to other native API calls under the hood:
      ITextureView *pRTVs[] = {m_pRTV}; m_pContext->SetRenderTargets(_countof( pRTVs ), pRTVs, m_pDSV); // Clear render target and depth buffer const float zero[4] = {0, 0, 0, 0}; m_pContext->ClearRenderTarget(nullptr, zero); m_pContext->ClearDepthStencil(nullptr, CLEAR_DEPTH_FLAG, 1.f); // Set vertex and index buffers IBuffer *buffer[] = {m_pVertexBuffer}; Uint32 offsets[] = {0}; Uint32 strides[] = {sizeof(MyVertex)}; m_pContext->SetVertexBuffers(0, 1, buffer, strides, offsets, SET_VERTEX_BUFFERS_FLAG_RESET); m_pContext->SetIndexBuffer(m_pIndexBuffer, 0); Different native APIs use various set of function to execute draw commands depending on command details (if the command is indexed, instanced or both, what offsets in the source buffers are used etc.). For instance, there are 5 draw commands in Direct3D11 and more than 9 commands in OpenGL with something like glDrawElementsInstancedBaseVertexBaseInstance not uncommon. Diligent Engine hides all details with single IDeviceContext::Draw() method that takes takes DrawAttribs structure as an argument. The structure members define all attributes required to perform the command (primitive topology, number of vertices or indices, if draw call is indexed or not, if draw call is instanced or not, if draw call is indirect or not, etc.). For example:
      DrawAttribs attrs; attrs.IsIndexed = true; attrs.IndexType = VT_UINT16; attrs.NumIndices = 36; attrs.Topology = PRIMITIVE_TOPOLOGY_TRIANGLE_LIST; pContext->Draw(attrs); For compute commands, there is IDeviceContext::DispatchCompute() method that takes DispatchComputeAttribs structure that defines compute grid dimension.
      Source Code
      Full engine source code is available on GitHub and is free to use. The repository contains two samples, asteroids performance benchmark and example Unity project that uses Diligent Engine in native plugin.
      AntTweakBar sample is Diligent Engine’s “Hello World” example.

       
      Atmospheric scattering sample is a more advanced example. It demonstrates how Diligent Engine can be used to implement various rendering tasks: loading textures from files, using complex shaders, rendering to multiple render targets, using compute shaders and unordered access views, etc.

      Asteroids performance benchmark is based on this demo developed by Intel. It renders 50,000 unique textured asteroids and allows comparing performance of Direct3D11 and Direct3D12 implementations. Every asteroid is a combination of one of 1000 unique meshes and one of 10 unique textures.

      Finally, there is an example project that shows how Diligent Engine can be integrated with Unity.

      Future Work
      The engine is under active development. It currently supports Windows desktop, Universal Windows and Android platforms. Direct3D11, Direct3D12, OpenGL/GLES backends are now feature complete. Vulkan backend is coming next, and support for more platforms is planned.
    • By michaeldodis
      I've started building a small library, that can render pie menu GUI in legacy opengl, planning to add some traditional elements of course.
      It's interface is similar to something you'd see in IMGUI. It's written in C.
      Early version of the library
      I'd really love to hear anyone's thoughts on this, any suggestions on what features you'd want to see in a library like this? 
      Thanks in advance!
    • By Michael Aganier
      I have this 2D game which currently eats up to 200k draw calls per frame. The performance is acceptable, but I want a lot more than that. I need to batch my sprite drawing, but I'm not sure what's the best way in OpenGL 3.3 (to keep compatibility with older machines).
      Each individual sprite move independently almost every frame and their is a variety of textures and animations. What's the fastest way to render a lot of dynamic sprites? Should I map all my data to the GPU and update it all the time? Should I setup my data in the RAM and send it to the GPU all at once? Should I use one draw call per sprite and let the matrices apply the transformations or should I compute the transformations in a world vbo on the CPU so that they can be rendered by a single draw call?
    • By zolgoz
      Hi!

      I've recently started with opengl and just managed to write my first shader using the phong model. I want to learn more but I don't know where to begin, does anyone know of good articles or algorithms to start with?
      Thanks in advance.
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