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OpenGL little question about drawelement

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hi @all i play around with openGL since a few days and now i want to create an 50x50grid for example (base for landscapes) i play around with the examples from redbook but how can i add here texturecoordinates and normals to the code here? google/nehe/codesampler/etc offers me no real tutorial "in one piece" to learn about drawelements, only little pieces i am not able to complete so i took that way to pick sample of rebook that works and learn by modifying that but my question is: how can i add my textures and normal coordinates to that 'v' thing and how use the texture in draw call then ? and p.s.: if you can tell me where to activate z buffer ;)

#define NFACE 6
#define NVERT 8
void drawCube(GLdouble x0, GLdouble x1, GLdouble y0,
GLdouble y1, GLdouble z0, GLdouble z1)
{
static GLfloat v[8][3];
static GLfloat c[8][4] = {
{0.0, 0.0, 0.0, 1.0}, {1.0, 0.0, 0.0, 1.0},
{0.0, 1.0, 0.0, 1.0}, {1.0, 1.0, 0.0, 1.0},
{0.0, 0.0, 1.0, 1.0}, {1.0, 0.0, 1.0, 1.0},
{0.0, 1.0, 1.0, 1.0}, {1.0, 1.0, 1.0, 1.0}
};
/* indices of front, top, left, bottom, right, back faces */
static GLubyte indices[NFACE][4] = {
{4, 5, 6, 7}, {2, 3, 7, 6}, {0, 4, 7, 3},
{0, 1, 5, 4}, {1, 5, 6, 2}, {0, 3, 2, 1}
};

....

// Vertices Positions 
v[0][0] = v[3][0] = v[4][0] = v[7][0] = x0;
v[1][0] = v[2][0] = v[5][0] = v[6][0] = x1;
v[0][1] = v[1][1] = v[4][1] = v[5][1] = y0;
v[2][1] = v[3][1] = v[6][1] = v[7][1] = y1;
v[0][2] = v[1][2] = v[2][2] = v[3][2] = z0;
v[4][2] = v[5][2] = v[6][2] = v[7][2] = z1;

//Normal Positions

// ????

// Texture Positions

// ????



//drawing example 


glEnable (GL_DEPTH_TEST);  // Z buffer is not working

glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, g_textureID[0]); 

glEnableClientState (GL_VERTEX_ARRAY);
glEnableClientState (GL_COLOR_ARRAY);
glVertexPointer (3, GL_FLOAT, 0, v);
glColorPointer (4, GL_FLOAT, 0, c);

** ?!?!  glNORMALPointer (3, GL_FLOAT, 0, v);
** ?!?! glTEXTUREPointer (2, GL_FLOAT, 0, v);

glDrawElements(GL_QUADS, NFACE*4, GL_UNSIGNED_BYTE, indices);

glDisableClientState (GL_VERTEX_ARRAY);
glDisableClientState (GL_COLOR_ARRAY);

can you help me? much thx for all answers :) p.s.: i hate google

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You don't "add" your normals and texture coordinates to the 'v' buffer -- you just create them in their own buffers, like you did with the colors (the 'c' buffer). For example:
static GLfloat t[8][2] = {
{ ...your texture coords go here... },
};

Then call:
glTexCoordPointer(2, GL_FLOAT, 0, t);
...as you already have. And don't forget to enable GL_TEXTURE_COORD_ARRAY.

The same style goes for normals too.

As for your Z buffer not working, it's possible you're not creating it when you initialize the pixel format. Or it could be you're not clearing it either (setting GL_DEPTH_BUFFER_BIT when calling glClear). I'd need to see more code to tell you exactly.

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much thankx.. i start to understand how it works :)

and i works ..the textures are working perfekt
-> glTexCoordPointer (2, GL_FLOAT, 0, t);


what is the correct spell for normals to activate
like glTexNormalPointer (3, GL_FLOAT, 0, n) ; ?


for Z buffer, here
is my initialisation (fullscreen)
and start of my main(render)

much thx :)




void init( void)
{

EnumDisplaySettings( NULL, ENUM_CURRENT_SETTINGS, &g_oldDevMode );

int nMode = 0;
DEVMODE devMode;
bool bDesiredDevModeFound = false;

while( EnumDisplaySettings( NULL, nMode++, &devMode ) )
{

if( devMode.dmPelsWidth != reso_x || devMode.dmPelsHeight != reso_y)
continue;

// Does this device mode support 32-bit color?
if( devMode.dmBitsPerPel != 32 )
continue;

// Does this device mode support a refresh rate of 75 MHz?
if( devMode.dmDisplayFrequency != 75 )
continue;

// We found a match, but can it be set without rebooting?
if( ChangeDisplaySettings( &devMode, CDS_TEST ) == DISP_CHANGE_SUCCESSFUL )
{
bDesiredDevModeFound = true;
break;
}
}

if( bDesiredDevModeFound == false )
{
// TO DO: Handle lack of support for desired mode...
return;
}

//
// Verify hardware support by enumerating pixel formats...
//

g_hDC = GetDC( g_hWnd );

PIXELFORMATDESCRIPTOR pfd;

int nTotalFormats = DescribePixelFormat( g_hDC, 1, sizeof(pfd), NULL );

int nPixelFormat;

for( nPixelFormat = 1; nPixelFormat <= nTotalFormats; ++nPixelFormat )
{
if( DescribePixelFormat( g_hDC, nPixelFormat, sizeof(pfd), &pfd ) == 0 )
{
DWORD dwErrorCode = GetLastError();
// TO DO: Respond to failure of DescribePixelFormat
return;
}

if( !(pfd.dwFlags & PFD_SUPPORT_OPENGL) )
continue;

if( !(pfd.dwFlags & PFD_DOUBLEBUFFER) )
continue;

if( !(pfd.dwFlags & PFD_DRAW_TO_WINDOW) && fullscreen==0 )
continue;

if( pfd.iPixelType != PFD_TYPE_RGBA )
continue;

if( pfd.cColorBits != 32 )
continue;

if( pfd.cDepthBits != 16 )
continue;

// If we made it this far, we found a match!
break;
}

//
// Everything checks out - create the rendering context and
// switch the display settings with our new device mode...
//
if( SetPixelFormat( g_hDC, nPixelFormat, &pfd) == FALSE )
{
DWORD dwErrorCode = GetLastError();
// TO DO: Respond to failure of SetPixelFormat
return;
}

g_hRC = wglCreateContext( g_hDC );
wglMakeCurrent( g_hDC, g_hRC );


if( ChangeDisplaySettings( &devMode, CDS_FULLSCREEN ) != DISP_CHANGE_SUCCESSFUL )
{
// TO DO: Respond to failure of ChangeDisplaySettings
return;
}


loadTexture();

// Setup inits

glClearColor( 0.0f, 0.0f, 0.2f, 1.0f );
glEnable(GL_TEXTURE_2D);

glEnable (GL_DEPTH_TEST);


glMatrixMode( GL_PROJECTION );
glLoadIdentity();
gluPerspective( 45.0, (GLdouble)reso_x / reso_y, 0.0001, 100.0 );

int nNumTextureUnits = 0;
glGetIntegerv( GL_MAX_TEXTURE_UNITS_ARB, &nNumTextureUnits );

ShowCursor(false);
}



........................


void render( void )
{
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

//draw_land();


glMatrixMode( GL_MODELVIEW );
glLoadIdentity();


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Normals work fine now :)

but the Z Buffer problem is still there



void render( void )
{
glDepthFunc(GL_LESS);
glClearDepth(1.0);

glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );




another thing i see now.. if the object hit the borders
the texture positions seems to be moved at this vertice
that are out of the screen.


much thanx for your time :)

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hurray ... i got it !!!!


in the init of opengl was the error!


-> //if( !(pfd.dwFlags & PFD_DRAW_TO_WINDOW) && fullscreen==0 )continue;

-> if( pfd.cDepthBits != 16 ) continue;

after diabling thoose two lines
the Z Buffer error was complete away,
the textures painted normal
and

the FPS raised from 6 FPS to 91 FPS



much much thankx for your fast help :)

(i post some screenshots when i get better with opengl ,
my networkcode and other things runs perfect
we work on an mmorpg and we decided to move from directx to opengl
and i need to reprogramm all basic graphic parts of the engine.
(to avoid the xp/vista chaos that will hit much gamers)
(the game is a bit like the old ultima online..in 3d but with old touch)

greetings sven













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Quote:
Original post by Aragon
in the init of opengl was the error!


-> //if( !(pfd.dwFlags & PFD_DRAW_TO_WINDOW) && fullscreen==0 )continue;

-> if( pfd.cDepthBits != 16 ) continue;

after diabling thoose two lines
the Z Buffer error was complete away,
the textures painted normal
and

the FPS raised from 6 FPS to 91 FPS


Hmm... it sounds like the pixel format checking code picked the Microsoft OpenGL driver, rather than your video card's driver.

It _might_ be that a cDepthBits of 16 wasn't good -- perhaps 24 would work better?

Glad it's fixed, though! :)

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...thats very possible

i will work on the code to avoid such problems again,
but first i have to get much much deeper into openGL
to understand it..but i get quicker results
with opengl than with directx... thats absolut great

z buffer is working, index buffers working,
lighting is now working.. alpha transparency and colorkeying
is working..

what a wonderfull day :)

much thx again



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      normalize all the vertices on my vertex shader i can get a perfect sphere.
      T = glm::translate(glm::dmat4(1.0), glm::dvec3(0.0, 0.0, 1.0)); R = glm::rotate(glm::dmat4(1.0), glm::radians(180.0), glm::dvec3(1.0, 0.0, 0.0)); sides[0] = new TerrainNode(1.0, radius, T * R, glm::dvec2(0.0, 0.0), new TerrainTile(1.0, SIDE_FRONT)); T = glm::translate(glm::dmat4(1.0), glm::dvec3(0.0, 0.0, -1.0)); R = glm::rotate(glm::dmat4(1.0), glm::radians(0.0), glm::dvec3(1.0, 0.0, 0.0)); sides[1] = new TerrainNode(1.0, radius, R * T, glm::dvec2(0.0, 0.0), new TerrainTile(1.0, SIDE_BACK)); // So on and so forth for the rest of the sides As you can see, for the front side grid, i rotate it 180 degrees to make it face the camera and push it towards the eye;
      the back side is handled almost the same way only that i don't need to rotate it but simply push it away from the eye.
      The same technique is applied for the rest of the faces (obviously, with the proper rotations / translations).
      The matrix that result from the multiplication of R and T (in that particular order) is send to my vertex shader as `r_Grid'.
      // spherify vec3 V = normalize((r_Grid * vec4(r_Vertex, 1.0)).xyz); gl_Position = r_ModelViewProjection * vec4(V, 1.0); The `r_ModelViewProjection' matrix is generated on the CPU in this manner.
      // No the most efficient way, but it works. glm::dmat4 Camera::getMatrix() { // Create the view matrix // Roll, Yaw and Pitch are all quaternions. glm::dmat4 View = glm::toMat4(Roll) * glm::toMat4(Pitch) * glm::toMat4(Yaw); // The model matrix is generated by translating in the oposite direction of the camera. glm::dmat4 Model = glm::translate(glm::dmat4(1.0), -Position); // Projection = glm::perspective(fovY, aspect, zNear, zFar); // zNear = 0.1, zFar = 1.0995116e12 return Projection * View * Model; } I managed to get rid of z-fighting by using a technique called Logarithmic Depth Buffer described in this article; it works amazingly well, no z-fighting at all, at least not visible.
      Each frame i'm rendering each node by sending the generated matrices this way.
      // set the r_ModelViewProjection uniform // Sneak in the mRadiusMatrix which is a matrix that contains the radius of my planet. Shader::setUniform(0, Camera::getInstance()->getMatrix() * mRadiusMatrix); // set the r_Grid matrix uniform i created earlier. Shader::setUniform(1, r_Grid); grid->render(); My planet's radius is around 6400000.0 units, absurdly large, but that's what i really want to achieve;
      Everything works well, the node's split and merge as you'd expect, however whenever i get close to the surface
      of the planet the rounding errors start to kick in giving me that lovely stairs effect.
      I've read that if i could render each grid relative to the camera i could get better precision on the surface, effectively
      getting rid of those rounding errors.
       
      My question is how can i achieve this relative to camera rendering in my scenario here?
      I know that i have to do most of the work on the CPU with double, and that's exactly what i'm doing.
      I only use double on the CPU side where i also do most of the matrix multiplications.
      As you can see from my vertex shader i only do the usual r_ModelViewProjection * (some vertex coords).
       
      Thank you for your suggestions!
       
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