B3D brush and texture blend modes (GL equivalents)

BlitzMax Forums/OpenGL Module/B3D brush and texture blend modes (GL equivalents)

AdrianT (Posted 2005) [#1]

I was wondering if anyone had the information in regards to what each of these are in OpenGL. Coukdn't find a proper answer using the search feature of the forums. Any help would be useful. I'm not sure whether the brush and texure blendmodes are actually the samething so I listed them seperately. BRUSH BLENDMODES: Alpha: Multiply: Add: TEXTURE BLENDMODES Alpha: Multiply: Add: Dot3: Modulate2X:

ImaginaryHuman (Posted 2005) [#2]

I am not familiar with Blitz3D. But in BlitzMax, `Alpha` is SetBlend ALPHABLEND `Add` is SetBlend LIGHTBLEND `Multiply` is SetBlend SHADEBLEND I don't know what the Dot3 or Modulate 2X do. You might look at setting up your own modes with glBlendFunc() and glEnable(GL_BLEND). You might be able to use glBlendFunc(SRC_ALPHA_SATURATE,GL_ONE) to achieve something like a `2x` modulation, but I have no idea if thats the same thing.

AdrianT (Posted 2005) [#3]

thanks :) thats a good start anyway :)

Vertex (Posted 2005) [#4]

Hi! Dot3: ' glActiveTexture GL_TEXTURE0+Layer ' glBindTexture GL_TEXTURE_2D, MyNormalMap glTexEnvf GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT glTexEnvf GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_DOT3_RGB_EXT Add: glTexEnvf GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_ADD Modulate: glTexEnvf GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_MODULATE One texture: glTexEnvf GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_REPLACE cu olli

Duck (Posted 2006) [#5]

Hi, Here's Modulate2x: '--------------------------------------------------------------------------- 'grass texture glActiveTextureArb(GL_TEXTURE0_ARB) glEnable(GL_TEXTURE_2D) glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE) glBindTexture(GL_TEXTURE_2D, grassTex) 'lightmap using modulate2x glActiveTextureArb(GL_TEXTURE1_ARB) glEnable(GL_TEXTURE_2D) glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE) glTexEnvi(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_MODULATE) glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PREVIOUS) glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND0_RGB, GL_SRC_COLOR) glTexEnvi(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE) glTexEnvi(GL_TEXTURE_ENV, GL_OPERAND1_RGB, GL_SRC_COLOR) glTexEnvi(GL_TEXTURE_ENV, GL_RGB_SCALE, 2.0) glBindTexture(GL_TEXTURE_2D, lightMapTex) '----------------------------------------------------------------------- You can also get 4x by changing 2.0 to 4.0 in "glTexEnvi(GL_TEXTURE_ENV, GL_RGB_SCALE, 2.0)"

ImaginaryHuman (Posted 2006) [#6]

What version of GL does that modulate need? Or an extension?

Duck (Posted 2006) [#7]

OpenGL 1.1 and ARB_multitexture are required for this extension. The ARB description is at : http://oss.sgi.com/projects/ogl-sample/registry/ARB/texture_env_combine.txt I tried this out with BlitzMax and everything was ok.