glTexCoordPointer and multi texturing

OpenGL OpenGL: Advanced Coding
1

Hi,

I wonder if I have found a driver bug.

After reading a bit in the red book I came to the understanding that you should use:

for (int i = 0; i < numTexturesUsed; i++)
{
glClientActiveTexture(GL_TEXTURE0 + i);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glTexCoordPointer(2, GL_FLOAT, 0, texCoordBuffer[i]);
}

To set up texture coordinate arrays in multitexturing.

But it seems like I have been mistaken…

The code doesn’t work as intended and if I use:

int numTextureUnits = 1;
glGetIntegerv(GL_MAX_TEXTURE_UNITS_ARB, &numTextureUnits);

for (int i = 0; i < numTextureUnits; i++)
{
glActiveTextureARB(GL_TEXTURE0_ARB + i);
int enabled = glIsEnabled(GL_TEXTURE_COORD_ARRAY),
}

Then all the texture units reports “enabled” even though I only have numTexturesUsed = 1.

Any help on how to get this working appreciated!

Thanks,
Peter

2

What do you mean by

Originally posted by PeterP:
Then all the texture units reports “enabled” even though I only have numTexturesUsed = 1.

3

Thanks for taking the time.

In the first code section numTexturesUsed = 1.

In the second code section I loop though all four texture units (on my GeForce4).

I was expecting that the first texture unit should report “enabled” and the other three texture units should report “not enabled”.

But instead all four texture units have texture coordinates enabled.

4

That’s because your second piece of code is incorrect. Change it to this:

for (int i = 0; i < numTextureUnits; i++)
	{
		glClientActiveTexture(GL_TEXTURE0 + i);
		int enabled = glIsEnabled(GL_TEXTURE_COORD_ARRAY);
	}

and it’ll work as expected.

5

Ah…

thanks!

6

By the way, if you think you’ve found a driver bug, it’s helpful to mention the driver and hardware that you think has the bug.

In this case, it clearly isn’t a driver bug, but in general that kind of information is good for those of us whose job it is to create driver bugs. :slight_smile:

Pat