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OpenGL opengl in hardware mode

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I was wondering how you know if opengl is running in hardware mode or software mode. I made a surface with GL_QUADS that was 1 * 1 big, the did 2 for loops to draw that surface to be 200 * 200 (while using glTranslate...) and added a texture to it and if I don''t use the textures, I get about 60 fps and if I add the texture which is 96 pixels by 96 pixels, I get fps ranging from 21 to 18. I was just wondering if I might be running in software mode instead of hardware mode and this would be why my little program is sooo slow. thx for any help in advance.. ashtray.. ...

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Guest Anonymous Poster
Make sure you don''t load the texture each frame, instead of loading it once at the beginning of your program. This would explain the huge fps decrease.

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quote:
Original post by ashtray
if I add the texture which is 96 pixels by 96 pixels, I get fps ranging from 21 to 18.


...



If your not using any new extension your texture must have dimensions of 2^x at each side..

2^x will never be 96 if x is an integer.. make it 64*64 or 128*128

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and of course dont bind it for every single quad. also if you use immediate mode and a lot of glvertex calls then doing translate AND glvertex means twice more work then necessary.

and yes, using "odd" texture sizes might be possible by now, but its still slow.

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quote:
Original post by ashtray
I was wondering how you know if opengl is running in hardware mode or software mode.


In windows, glGet with GL_VENDOR and GL_RENDERER. If you see something like ''Generic microsoft'' you''re getting the software fallback. Typically you''ll see the name of the manufacturer of your video card.

But you could still be getting a non-accelerated display, most commonly if you request a funny/non-standard framebuffer format (nVidia cards tend to baulk at having high/mismatched depth and stencil bits on a 16bit desktop for example).

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Guest Anonymous Poster
Hello,

I changed my texture to be of size 128 * 128

I what I meant by 96 * 96 was dots per inch (the resolution), does this need to be changed as well? or does my 128 pixels * 128 pixels new size good now keeping the same resolution?


I am also binding once, before my loops,

I think I''m doing something wrong because it''s still very slow...

Here''s my code...

in my render function I have this building my "ground or floor"

void render()
{

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
int i, j;

glEnable(GL_TEXTURE_2D);

glBindTexture( GL_TEXTURE_2D, grassTexture );
for (i = 0; i <= 200; i++ ) {
for (j = 0; j <= 200; j++ ) { // largeur 3.1m
glPushMatrix();
glTranslatef( i, 0.0f, j );
glCallList(floor_display_list);
glPopMatrix();
}
}

glDisable(GL_TEXTURE_2D);

glFlush(); // Flush drawing commands
glutSwapBuffers();

}

and the display list function for creating my "floor" is

void drawFloor() {

glBegin(GL_QUADS);
glVertex3f( 0.0f, 0.0f, 0.0f);
glTexCoord2f( 0.0f, 0.0f);
glVertex3f( 1.0f, 0.0f, 0.0f);
glTexCoord2f( 1.0f, 0.0f);
glVertex3f( 1.0f, 0.0f, 1.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f( 0.0f, 0.0f, 1.0f);
glTexCoord2f(0.0f, 1.0f);
glEnd();
}

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This is the version info (and more) that I am using.

From what I understand, I am in hardware mode... right?

GL_VENDOR -> NVIDIA Corporation
GL_RENDERER -> GeForce4 MX 420 with AGP8X/AGP/3DNOW!
GL_VERSION -> 1.3.1
GL_EXTENSIONS -> GL_ARB_imaging GL_ARB_multitexture GL_ARB_texture_compression GL_ARB_texture_cube_map GL_ARB_texture_env_add GL_ARB_texture_env_combine GL_ARB_texture_env_dot3 GL_ARB_transpose_matrix GL_S3_s3tc GL_EXT_abgr GL_EXT_bgra GL_EXT_blend_color GL_EXT_blend_minmax GL_EXT_blend_subtract GL_EXT_clip_volume_hint GL_EXT_compiled_vertex_array GL_EXT_draw_range_elements GL_EXT_fog_coord GL_EXT_multi_draw_arrays GL_EXT_packed_pixels GL_EXT_paletted_texture GL_EXT_point_parameters GL_EXT_rescale_normal GL_EXT_secondary_color GL_EXT_separate_specular_color GL_EXT_shared_texture_palette GL_EXT_stencil_wrap GL_EXT_texture_compression_s3tc GL_EXT_texture_edge_clamp GL_EXT_texture_env_add GL_EXT_texture_env_combine GL_EXT_texture_env_dot3 GL_EXT_texture_cube_map GL_EXT_texture_filter_anisotropic GL_EXT_texture_lod GL_EXT_texture_lod_bias GL_EXT_texture_object GL_EXT_vertex_array GL_EXT_vertex_weighting GL_IBM_texture_mirrored_repeat GL_KTX_buffer_region GL_NV_blend_square GL_NV_evaluators GL_NV_fence GL_NV_fog_distance GL_NV_light_max_exponent GL_NV_packed_depth_stencil GL_NV_register_combiners GL_NV_texgen_emboss GL_NV_texgen_reflection GL_NV_texture_env_combine4 GL_NV_texture_rectangle GL_NV_vertex_array_range GL_NV_vertex_array_range2 GL_NV_vertex_program GL_NV_vertex_program1_1 GL_SGIS_generate_mipmap GL_SGIS_multitexture GL_SGIS_texture

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quote:

glBindTexture( GL_TEXTURE_2D, grassTexture );
for (i = 0; i <= 200; i++ ) {
for (j = 0; j <= 200; j++ ) { // largeur 3.1m
glPushMatrix();
glTranslatef( i, 0.0f, j );
glCallList(floor_display_list);
glPopMatrix();
}
}


There are two major performance sinks in this code, and a multitude of smaller ones.

The to big problems are the matrix stuff, and the display list call. You are basically performing more than 40000 matrix multiplication and display list calls per frame ! No wonder, that this is slow. Try this instead:


glBindTexture( GL_TEXTURE_2D, grassTexture );
glBegin(GL_QUADS);
for (i = 0; i <= 200; i++ ) {
for (j = 0; j <= 200; j++ ) { // largeur 3.1m

glTexCoord2f( 0.0f, 0.0f);
glVertex3f( i, 0.0f, j);
glTexCoord2f( 1.0f, 0.0f);
glVertex3f( i+1, 0.0f, j);
glTexCoord2f(1.0f, 1.0f);
glVertex3f( i+1, 0.0f, j+1);
glTexCoord2f(0.0f, 1.0f);
glVertex3f( i, 0.0f, j+1);
}
}
glEnd();


Oh, and there was a bug with the texture coordinates, btw: you have to set the vertex attributes (such as texcoords) before sending the vertex position (which will dispatch the vertex to the GPU).

This code above can of course still be tremendeously optimized: using triangle strips, for example. You''ll get the greatest performance boost by dropping immediate mode altogether, and using vertex arrays (or variants).

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OK, thx for the tips.

I thought that using display list would increase my performance because the shape that I am drawing is already compiled. When should one use display lists? I though you did when you were repeating a patterns of something drawn.

Also, if I do use triangle strips, how would I go about adding a square texture onto the triangles. if I draw 2 triangles to make one square, how would I attach my texture to my new square.

I''ve looked for good tutorials on texturing but did not find anything that really suited my needs. How to attach it properly to the object, etc...

I also do not understand what you mean by "dropping immediate mode altogether, and using vertex arrays"

As you probably guessed, I''m new to opengl... what is "immediate mode"

I really appreciate you taking the time to answer my questions.

thx.


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about immediate mode,
I knew what it was but forgot it was called immediate mode...
(command is executed as soon as the server receives it) but doesn''t having a display list give it all in one shot? so the transformations and drawing that I''m doing count at one command and not 4 because they are pre-compiled?

I changed my code yo use yours (trashed the display list and fixed the tex coord (thx)) and I only gained 5 fps. I''m looking into triangle stips now.

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you were right about the triangle strips... They are much faster the the quads I was using.


I''m still confused about the display lists. What if I wanted to build cubes and pyramids on top (to make it look like a ''cheap'' house, would it be better to use display lists for that?





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quote:
Original post by ashtray
I''m still confused about the display lists. What if I wanted to build cubes and pyramids on top (to make it look like a ''cheap'' house, would it be better to use display lists for that?


Display lists are only faster when they contain a large amount of polys. I forget the exact number but they start being efficient at about ~400 tris. For small scale stuff like this its probably easier to use immediate mode, or try building one vertex array for the whole floor and then telling GL to render it all at once. Or better yet, build one vertex array at the start and only rebuild it when anything changes.

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I think I understand now. Is there a doc for optimization techniques comewhere?

SO what I can do is write a function that draws my initial landscape and only update it when something changes like movement ("walking" through my landscape) or any other graphic change or whatever.

Would I use the idleFunc for this? I never in any docs where or how to use that functions.

will this make navigation choppy?

I really appreciate your replies.

I had one more question... If I only use basically 2 big tris to make my whole 200 * 200, How would I attach my texture tiled if my texture is for example 1 * 1 (well, really 128 pixels * 128 pixels )? How would I be able to make it look like it''s been attached to 1*1 squares made of 2 tris and not attached just once on the 200 * 200 square?

If I should be in an other newsgroup... I can always post there..

thx.

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You could use diffrent u and v coordinates.
When you use for instance 5.0 instead of 1.0 as u and v coordinate the texture would be repeated 5 times.
But you must set the texture wrap mode correctly. Should be something like:

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,GL_REPEAT);

[edited by - Roland on August 10, 2003 5:34:23 AM]

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quote:
Original post by Trienco
and of course dont bind it for every single quad. also if you use immediate mode and a lot of glvertex calls then doing translate AND glvertex means twice more work then necessary.

and yes, using "odd" texture sizes might be possible by now, but its still slow.




if you use glu build mipmaps functions you can uses texture not multiple of 2



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U can still optimise the code further by using display lists.

You can compile your code into a display list at load time.
glNewList(GL_COMPILE,LISTNUMBER);
glBindTexture( GL_TEXTURE_2D, grassTexture );
glBegin(GL_QUADS);
for (i = 0; i <= 200; i++ ) {
for (j = 0; j <= 200; j++ ) { // largeur 3.1m
glTexCoord2f( 0.0f, 0.0f);
glVertex3f( i, 0.0f, j);
glTexCoord2f( 1.0f, 0.0f);
glVertex3f( i+1, 0.0f, j);
glTexCoord2f(1.0f, 1.0f);
glVertex3f( i+1, 0.0f, j+1);
glTexCoord2f(0.0f, 1.0f);
glVertex3f( i, 0.0f, j+1); }}
glEnd();
glEndList();

Then when u need to call it just use glCallList(LISTNUMBER).

You should see a huge performance gain because you are now making 1 call instead of 40 000.

[edited by - GamerSg on August 10, 2003 11:49:21 AM]

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quote:
Original post by Basiror
if you use glu build mipmaps functions you can uses texture not multiple of 2


nobody said you cant.. but just because its possible doesnt mean you should do it. though if i were a 3d api id probably just take that odd texture and blow it up to the next power of 2 size *fg*

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Hi there!

I''m making an RTS and I''m having the same problem...
major slowdowns as the polycount increases...
around 3-400 polys = unplayable...

So to optimize:

Minimize glPopMatrix,glPushMatrix calls...?

Build the entire map in a displaylist -( wouldn''t that be acctually slower than rendering each tile, only rendering the visible ones?)

Should I use glTranslate instead of pop/pushmatrix?

Minimize glBindTexture() .... How would I then change textures?
Do you mean, sort all units of the same type and then draw them in a loop...?

Right now I''m doing it this way:

for (int i = 1; i < NrOfUnits+1;i++)
{
glBindTexture(Unit.Texture);
glPushMatrix()
glTranslate(Unit[i].x,Unit[i].y,Unit[i].z);
glCallList(Unit[i].Model);
glPopMatrix();
}

Would it be better to sort all the units and then draw them in "order"?





"Game Maker For Life, probably never professional thou." =)

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      // 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 tutorials, sample applications, asteroids performance benchmark and an example Unity project that uses Diligent Engine in native plugin.
      Atmospheric scattering sample 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, Linux, Android, MacOS, and iOS platforms. Direct3D11, Direct3D12, OpenGL/GLES backends are now feature complete. Vulkan backend is coming next, and Metal backend is in the plan.
    • By LifeArtist
      Good Evening,
      I want to make a 2D game which involves displaying some debug information. Especially for collision, enemy sights and so on ...
      First of I was thinking about all those shapes which I need will need for debugging purposes: circles, rectangles, lines, polygons.
      I am really stucked right now because of the fundamental question:
      Where do I store my vertices positions for each line (object)? Currently I am not using a model matrix because I am using orthographic projection and set the final position within the VBO. That means that if I add a new line I would have to expand the "points" array and re-upload (recall glBufferData) it every time. The other method would be to use a model matrix and a fixed vbo for a line but it would be also messy to exactly create a line from (0,0) to (100,20) calculating the rotation and scale to make it fit.
      If I proceed with option 1 "updating the array each frame" I was thinking of having 4 draw calls every frame for the lines vao, polygons vao and so on. 
      In addition to that I am planning to use some sort of ECS based architecture. So the other question would be:
      Should I treat those debug objects as entities/components?
      For me it would make sense to treat them as entities but that's creates a new issue with the previous array approach because it would have for example a transform and render component. A special render component for debug objects (no texture etc) ... For me the transform component is also just a matrix but how would I then define a line?
      Treating them as components would'nt be a good idea in my eyes because then I would always need an entity. Well entity is just an id !? So maybe its a component?
      Regards,
      LifeArtist
    • By QQemka
      Hello. I am coding a small thingy in my spare time. All i want to achieve is to load a heightmap (as the lowest possible walking terrain), some static meshes (elements of the environment) and a dynamic character (meaning i can move, collide with heightmap/static meshes and hold a varying item in a hand ). Got a bunch of questions, or rather problems i can't find solution to myself. Nearly all are deal with graphics/gpu, not the coding part. My c++ is on high enough level.
      Let's go:
      Heightmap - i obviously want it to be textured, size is hardcoded to 256x256 squares. I can't have one huge texture stretched over entire terrain cause every pixel would be enormous. Thats why i decided to use 2 specified textures. First will be a tileset consisting of 16 square tiles (u v range from 0 to 0.25 for first tile and so on) and second a 256x256 buffer with 0-15 value representing index of the tile from tileset for every heigtmap square. Problem is, how do i blend the edges nicely and make some computationally cheap changes so its not obvious there are only 16 tiles? Is it possible to generate such terrain with some existing program?
      Collisions - i want to use bounding sphere and aabb. But should i store them for a model or entity instance? Meaning i have 20 same trees spawned using the same tree model, but every entity got its own transformation (position, scale etc). Storing collision component per instance grats faster access + is precalculated and transformed (takes additional memory, but who cares?), so i stick with this, right? What should i do if object is dynamically rotated? The aabb is no longer aligned and calculating per vertex min/max everytime object rotates/scales is pretty expensive, right?
      Drawing aabb - problem similar to above (storing aabb data per instance or model). This time in my opinion per model is enough since every instance also does not have own vertex buffer but uses the shared one (so 20 trees share reference to one tree model). So rendering aabb is about taking the model's aabb, transforming with instance matrix and voila. What about aabb vertex buffer (this is more of a cosmetic question, just curious, bumped onto it in time of writing this). Is it better to make it as 8 points and index buffer (12 lines), or only 2 vertices with min/max x/y/z and having the shaders dynamically generate 6 other vertices and draw the box? Or maybe there should be just ONE 1x1x1 cube box template moved/scaled per entity?
      What if one model got a diffuse texture and a normal map, and other has only diffuse? Should i pass some bool flag to shader with that info, or just assume that my game supports only diffuse maps without fancy stuff?
      There were several more but i forgot/solved them at time of writing
      Thanks in advance
    • By RenanRR
      Hi All,
      I'm reading the tutorials from learnOpengl site (nice site) and I'm having a question on the camera (https://learnopengl.com/Getting-started/Camera).
      I always saw the camera being manipulated with the lookat, but in tutorial I saw the camera being changed through the MVP arrays, which do not seem to be camera, but rather the scene that changes:
      Vertex Shader:
      #version 330 core layout (location = 0) in vec3 aPos; layout (location = 1) in vec2 aTexCoord; out vec2 TexCoord; uniform mat4 model; uniform mat4 view; uniform mat4 projection; void main() { gl_Position = projection * view * model * vec4(aPos, 1.0f); TexCoord = vec2(aTexCoord.x, aTexCoord.y); } then, the matrix manipulated:
      ..... glm::mat4 projection = glm::perspective(glm::radians(fov), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f); ourShader.setMat4("projection", projection); .... glm::mat4 view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp); ourShader.setMat4("view", view); .... model = glm::rotate(model, glm::radians(angle), glm::vec3(1.0f, 0.3f, 0.5f)); ourShader.setMat4("model", model);  
      So, some doubts:
      - Why use it like that?
      - Is it okay to manipulate the camera that way?
      -in this way, are not the vertex's positions that changes instead of the camera?
      - I need to pass MVP to all shaders of object in my scenes ?
       
      What it seems, is that the camera stands still and the scenery that changes...
      it's right?
       
       
      Thank you
       
    • By dpadam450
      Sampling a floating point texture where the alpha channel holds 4-bytes of packed data into the float. I don't know how to cast the raw memory to treat it as an integer so I can perform bit-shifting operations.

      int rgbValue = int(textureSample.w);//4 bytes of data packed as color
      // algorithm might not be correct and endianness might need switching.
      vec3 extractedData = vec3(  rgbValue & 0xFF000000,  (rgbValue << 8) & 0xFF000000, (rgbValue << 16) & 0xFF000000);
      extractedData /= 255.0f;
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