   Rendering to float textures
  The only configuration that allows me to render to float texture is this one:glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32F_ARB, width, height, 0, GL_RGBA, GL_FLOAT, NULL);How can I perform rendering to float-red-only or float-red-green-only channels? I've tried extensions like GL_FLOAT_R32_NV but they simply don't work.   
  Oh, I'm sorry, I made a mistake... thought that GL_ALPHA32F_ARB doesn't work. I tried to "display" this alpha channel value and it didn't work. However, I made a simple fog-volume sample and it works!So now I can render to one-channel and four-channel float texture.But is there a way to use two-channel float texture?Such a configuration gives me errors:glTexImage2D(GL_TEXTURE_2D, 0, GL_FLOAT_RG32_NV, width, height, 0, GL_RED | GL_GREEN, GL_FLOAT, NULL);Besides, even if this would work, wouldn't it work only with NVidia GPUs?   ;  I think what you need is this extension -> http://www.opengl.org/registry/specs/ARB/texture_rg.txt   ;  Hmm... I see this extension is quite new, whereas in DX it's been for a long time.So how did people use RG-channel with OGL before? PBuffers?;  This is not valid for GLGL_RED | GL_GREENand also, since the last parameter is NULL, it doesn't matter. Just set it to GL_RGBA or GL_RED, GL_GREEN, GL_BLUE, ....Also, check outhttp://www.opengl.org/wiki/FAQ#2_component_textures;  How can I access luminance channel of GL_LUMINANCE16_ALPHA16 via shader then?;  Luminance is copied into r and g and b, alpha is in alpha channel.So something like thisuniform sampler2D texture;...texel = texture2D(texture,gl_TexCoord[0].st);...texel.a is alphatexel.r or texel.g or texel.b is luminance.Note values are scaled to [0..1] range in the vertex shader..thusIf you use 16 bit unsigned you need to scale back by 65535.0;  Thanks a lot :)   