Hello everyone,

I have recently been able to impement the simple bump/normal mapping technique for my hobby game engine. This technique is based on Nehe's tutorials and Paul Baker's relatice example. It only considers a single diffuse light.

This is the equation that I implement using just texture units.
color = max{l.n, 0}*diffuse

max{l.n, 0} <- this part is ok. It looks great and it's like the light source is white.

I'm trying to implement the diffuse color multiplication using modulation and by enabling the color arrays. My idea is to modulate the bump mapped texture with the GL_PRIMARY_COLOR. It doesn't work and it seems that I have no access to the primitive color fragments from texture unit 3.

this is my code. I use Vertex arrays

//Bind normalisation cube map to Texture Unit 0
m_extObj->glActiveTextureARB()(GL_TEXTURE0_ARB);
glEnable(GL_TEXTURE_CUBE_MAP_ARB);
glBindTexture(GL_TEXTURE_CUBE_MAP_ARB, m_imgObj->GetTexId(0));
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
glTexEnvf(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_REPLACE);
glTexEnvf(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_TEXTURE);
//Specify and enable Texture coordinates for cube map (sends tangent space light for normalisation-UNIT 0)
m_extObj->glClientActiveTextureARB()(GL_TEXTURE0_ARB);
glTexCoordPointer(3, GL_FLOAT, sizeof(CVertex), (void*)(5*sizeof(CVec3D)));
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
//Specify and enable Vertice coordinates
glVertexPointer(3, GL_FLOAT, sizeof(CVertex), 0);
glEnableClientState(GL_VERTEX_ARRAY);
//Specify and enable color arrays
glColorPointer(3, GL_FLOAT, sizeof(CVertex), (void*)(6*sizeof(CVec3D)));
glEnableClientState(GL_COLOR_ARRAY);

//Bind normal map to Texture Unit 1
m_extObj->glActiveTextureARB()(GL_TEXTURE1_ARB);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, m_imgObj->GetTexId(2));
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE);
glTexEnvf(GL_TEXTURE_ENV, GL_COMBINE_RGB, GL_DOT3_RGB);
glTexEnvf(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PREVIOUS);
glTexEnvf(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_TEXTURE);
//Specify and enable Texture coordinates for normal map texture
m_extObj->glClientActiveTextureARB()(GL_TEXTURE1_ARB);
glTexCoordPointer(2, GL_FLOAT, sizeof(CVertex), (void*)(sizeof(CVec3D)));
glEnableClientState(GL_TEXTURE_COORD_ARRAY);

//Bind texture to Texture Unit 2
m_extObj->glActiveTextureARB()(GL_TEXTURE2_ARB);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, m_imgObj->GetTexId(1));
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
//Specify and enable Texture coordinates for normal map texture
m_extObj->glClientActiveTextureARB()(GL_TEXTURE2_ARB);
glTexCoordPointer(2, GL_FLOAT, sizeof(CVertex), (void*)(sizeof(CVec3D)));
glEnableClientState(GL_TEXTURE_COORD_ARRAY);

//Material color by Texture Unit 3
m_extObj->glActiveTextureARB()(GL_TEXTURE3_ARB);
glDisable(GL_TEXTURE_2D);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
glTexEnvf(GL_TEXTURE_ENV, GL_SOURCE0_RGB, GL_PREVIOUS);
glTexEnvf(GL_TEXTURE_ENV, GL_SOURCE1_RGB, GL_PRIMARY_COLOR);


Can't I implement the above equation in a single pass?

Thanks!