glGenTextures() very very strange.....

OpenGL OpenGL: Basic Coding
1

Afternoon all,

I’ve got a function that generates a texture - enables GL_TEXTURE_2D generates a texture id (into a global UINT array) , checks it’s valid, binds it , disables GL_TEXTURE_2D (roughly)

anyway if the function returns void or a bool it’s fine BUT if i return the texture id generated or do anything with the id (set another variable equal to it, return it or anything) glGenTextures fails next time around.

i currently have three textures - the id’s if i dont do anything are 1,2,3.

if i do something like return it they are 1,1,1 (i have a glIsTexture() call below glGenTextures but it doesnt seem to do anything)

any ideas as this is incredibly weird and it’s stopping me proceeding…

???

Cheers

Allan

2

Heh, weird.

Code please

3

i’ll bring / post the code tomorrow (it’s at home) but the function is very simple (“does exactly what it says on the tin”) so this is something very odd.

A bit more info - i have my global texture id array and a global counter which i increment after generating a texture (so the next texture ID goes into the next array space) and if i return g_TextureID[g_TexCount] it works fine (returns the wrong id as we want g_TextureID[g_TexCount-1]
(which causes the headache described above)

head off table weird…

4

Here’s the code function i’ve been using - can anyone see what’s up?

BOOL CGLTexture::GenerateTextures(CRendererMeshFormat *pMesh, CTGAFile *pTGAFile)
{
glEnable(GL_TEXTURE_2D);

glGenTextures(1, &g_uiTextureID[g_TexCount]);

TRACE("pMesh->uiTexID = %d

", g_uiTextureID[g_TexCount]);

if(glIsTexture(g_uiTextureID[g_TexCount]) == GL_TRUE)
{
	TRACE("ERROR : Texture Name Already Taken!

");
return FALSE;
}

glBindTexture(GL_TEXTURE_2D, g_uiTextureID[g_TexCount]);	

// TGA's use BGR so the data needs to be read in and converted or you can use GL_BGR_EXT

UINT uiWidth		= pTGAFile->GetImageWidth();
UINT uiHeight		= pTGAFile->GetImageHeight();
BYTE *pImageData	= pTGAFile->m_pImageData; 

glTexImage2D (GL_TEXTURE_2D, 0, GL_RGB, uiWidth, uiHeight, 0, GL_BGR_EXT, GL_UNSIGNED_BYTE, pImageData);

glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);	
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);								

glDisable(GL_TEXTURE_2D);

g_TexCount++;

return TRUE;

}

if i try to do ANYTHING with g_uiTextureID[g_TexCount]); (or g_uiTextureID[g_TexCount-1]) after incrementing g_TexCount; the tex id’s returned are all wrong (1 for every
single one)

Anybody?

5

if it were C I would say memory error somewhere in your code