   Multi-texture Blending
  helloI'm working on Multi-texture Blending using openglso ,I need some information about this;1)  create some textures ;2)  Loadtexture  int to renderUnits like this    //--------    glActiveTextureARB( GL_TEXTURE0_ARB );    glEnable( GL_TEXTURE_2D );    glBindTexture( GL_TEXTURE_2D, TextureId);.....   //----------3) should tell opengl how to compute colors in those  textures    How to do 3)?4) set texture-coord...5) Disable  ActiveTextureARB like this:   //-----------  glActiveTextureARB(GL_TEXTURE0_ARB);  glDisable(GL_TEXTURE_2D);   //---------but what does this code means //----------glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_INTERPOLATE_ARB ); glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_PREVIOUS_ARB );glTexEnvi( GL_TEXTURE_ENV, GL_OPERAND0_RGB_ARB, GL_SRC_COLOR );glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_TEXTURE );glTexEnvi( GL_TEXTURE_ENV, GL_OPERAND1_RGB_ARB, GL_SRC_COLOR );glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE2_RGB_ARB, GL_PRIMARY_COLOR_ARB);glTexEnvi( GL_TEXTURE_ENV, GL_OPERAND2_RGB_ARB, GL_SRC_COLOR );//-----------------------en ..... thanks   
  The code you have listed provides different blending options for the textures stored in the texture units. Operations such as add, multiply, substract, interpolate, etc.There is a tool app which will help you to choose the right parameters for the effect you are looking for. I should have it at home, so I'll be able to provide you the name in about 8 hours or so ;-)Generally you have - SOURCE1 which is source of first texture.- SOURCE2 - // -- OPERANDx which is the operation you wish to perform between the two textures- Parameter on which it should work.I'm quite sure you will find a lot about those in MSDN, if you look up glTexEnvi, or one of the constants for the operations.;  MSDN doesn't have such information. If you find it, let us know.You can find that kind of information in the GL spechttp://opengl.org/documentation/specs/