Multitexturing with Lightmaps

OpenGL OpenGL: Basic Coding
1

Hi,

I want to render a floor with 10*10 tiled floor-textures and a non-tiled lightmap. The lightmap shouldn’t cover the whole area of the quad, for example only 1/10 of the area. How can I move the Lightmap in any position that I want?

Here is my code:

        glActiveTexture(GL_TEXTURE0); //floor
        glEnable(GL_TEXTURE_2D); 
        glBindTexture(GL_TEXTURE_2D, texture[0]); 
        glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT); 
        glTexEnvf (GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_REPLACE); 

//        glPushMatrix(); 
        glActiveTexture(GL_TEXTURE1); //lightmap 
        glEnable(GL_TEXTURE_2D); 
        glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT); 
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP); //no wrap 
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP); 
        glMatrixMode(GL_TEXTURE); 
        glLoadIdentity(); 
        glTranslatef(-1.0f,0.0f, 0.0f);  //move lightmap 
        glBindTexture(GL_TEXTURE_2D, texture[39]); 
        glMatrixMode(GL_MODELVIEW); 
//        glPopMatrix(); 

        glBegin(GL_QUADS);  
            glNormal3f(0, 1, 0); 
              glMultiTexCoord2f(GL_TEXTURE0, 0.0f, 0.0f); 
            glMultiTexCoord2f(GL_TEXTURE1, 0.0f, 0.0f); 
            glVertex3f(0, 0, 0); 
            glMultiTexCoord2f(GL_TEXTURE0, 0.0f, 10.0f);  //size of texture: 1/10
            glMultiTexCoord2f(GL_TEXTURE1, 0.0f, 10.0f); 
            glVertex3f(0, 0, 49); 
            glMultiTexCoord2f(GL_TEXTURE0, 10.0f, 10.0f); 
            glMultiTexCoord2f(GL_TEXTURE1, 10.0f, 10.0f); 
            glVertex3f(49, 0, 49); 
              glMultiTexCoord2f(GL_TEXTURE0, 10.0f, 0.0f); 
            glMultiTexCoord2f(GL_TEXTURE1, 10.0f, 0.0f); 
            glVertex3f(49, 0, 0); 
        glEnd(); 

        glActiveTexture(GL_TEXTURE1); 
        glDisable(GL_TEXTURE_2D); 

        glActiveTexture(GL_TEXTURE0); 
        glDisable(GL_TEXTURE_2D);

My problem consist of the lightmap which will also be tiled.

2

I’m moving this to the beginners forum. You can move your lightmap around by adjusting the texture coordinates, and it’s repeating because you’re not binding it prior to changing its parameters.

– Tom

3

Can you give me a code snipet for this, because I don’t really understand how to realize that.
I want to illustrate my problem again with a little graphic:

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These are 3x4 tiled textures on one QUAD, but I will only light up one or maybe two of them. Therefore I don’t want to use a big lightmap for the whole area.