Mipmapping and MultiTexturing

OpenGL OpenGL: Advanced Coding
1

Hi, I’m trying to take a 512x512 texture, automatically generate mipmaps down to about 32x32 size, then render a plane with each mipmap level blended onto the plane. The effect would be taking an image and blending it with lower resolution versions of the image.

Is there any way to choose the mipmapping bias and then apply this to a multitexturing unit of its own?

e.g.

glActiveTexture(GL_TEXTURE0);
assignTexture(myTexture, biasOf1);
glActiveTexture(GL_TEXTURE1);
assignTexture(myTexture, biasOf2);

etc…

Then multitexture each GL_TEXTURE together?? Any advice would be great, I may be going about this totally wrong!

Thanks for your time!

Ben

2

straight from gdc2k_ogl_extensions.pdf:

EXT_texture_lod_bias
Controls mipmap level-of-detail
• Increasing the per-texture LOD bias causes
– can improve texturing performance
– extra texture blurring (decreasing causes over-sharpening)
• Exactly like Direct3D’s texture LOD bias functionality
• Bias is a floating-point number; 1.0 is up one mipmap level
• glTexParameterf(GL_TEXTURE_FILTER_CONTROL_EXT,
GL_TEXTURE_LOD_BIAS_EXT, 0.25);
EXT_texture_lod_bias

3

That should be glTexEnvf(), not glTexParameterf().

– Tom

4

Thanks for your help, that’s great!

Ben.