Tuesday, August 04, 2009

Disabling Texture Units

After I managed to create multitextured polygons, I ran into another problem. After flushing the multitextured vertex array, I needed to flush a single textured vertex array for the HUD (Heads-up display, i.e. timer, score etc). The problem looked like it was using the texture coordinates of the previous vertex array.

After some googling and trying to understand what was happening, I realized that I needed to disable the 2nd texture unit. When you are using texture array pointers we use glClientActiveTexture, so before drawing the non-multitextured vertex array, I needed to disable the second texture unit and then switch back to the first texture unit

//disable 2nd texture unit
glDisable (GL_TEXTURE_2D);
//back to the 1st texture unit
glBindTexture(GL_TEXTURE_2D, [_texture name]);

Initially I tried using glActiveTexture instead of glClientActiveTexture. The glActiveTexture is used when display lists/immediate mode is used (glBegin...glEnd). And obviously nothing was happening.

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