I just finished getting the splot light shadowing mapping to work and I would like to extend it to a point light. I’m targeting OpenGL 3.3 .
I need help understanding how to set up the camera matrices for the cube faces and the how to sample the cube map
To setup the shadow map I’m doing this:
GLuint shadowMap;
GLuint fbo[6];
glBindTexture ( GL_TEXTURE_CUBE_MAP, &shadowMap );
glTexParameteri( GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
glTexParameteri( GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
glTexParameterf( GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
glTexParameterf( GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
glTexParameterf( GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE );
glTexParameterf( GL_TEXTURE_CUBE_MAP, GL_TEXTURE_COMPARE_MODE, GL_COMPARE_R_TO_TEXTURE );
glTexParameterf( GL_TEXTURE_CUBE_MAP, GL_TEXTURE_COMPARE_FUNC, GL_LEQUAL);
glGenFramebuffers( 6, fbo );
for ( i=0; i<6; i++ )
{
glTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_X+i, 0, GL_DEPTH_COMPONENT32F, 1024, 1024, 0, GL_DEPTH_COMPONENT, GL_FLOAT, 0 );
glBindFramebuffer( GL_FRAMEBUFFER, fbo[i] );
// disable color buffer, only need depth. Is this the right way to do this?
glDrawBuffer( GL_NONE );
glReadBuffer( GL_NONE );
// attach the texture to FBO depth attachment point
glFramebufferTexture2D( GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_CUBE_MAP_POSITIVE_X+i, shadowMap, 0 );
}
To update the shadow map, I’m trying something like ( at some point I intend to do this in a single pass, but one step at a time 
):
int f;
MatrixPerspective( &lightProjection, &identity, 90.0f, 1.0f, 2.0f, 200.0f ); // fov, aspect, near, far
glEnable ( GL_DEPTH_TEST ); // yes, depth test
glDisable ( GL_BLEND ); // no blending
glDisable ( GL_CULL_FACE ); // no culling
glDepthMask ( GL_TRUE ); // yes, write to depth buffer
glDisable ( GL_TEXTURE_2D ); // no texturing
glDisable ( GL_ALPHA_TEST ); // no alpha testing
glPolygonOffset( 4.0f, 32.0f );
glEnable(GL_POLYGON_OFFSET_FILL);
for ( f=0; f<6; f++ )
{
// create a matrix in the space of the light that faces each of the six directions
MatrixModelView( &lightModelview, f, &light->position, &light->orientation );
glBindFramebuffer( GL_FRAMEBUFFER, fbo[f] ); // switch rending to shadow map
glViewport ( 0,0, 1024, 1024 );
glClear ( GL_DEPTH_BUFFER_BIT );
glColorMask ( GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE );
RenderScene( &lightProjection, &lightModelview, scene, NULL, NULL );
}
glDisable(GL_POLYGON_OFFSET_FILL);
So my questions are:
How do I sample the cube map? So far I have this fragment shader:
uniform sampler2D diffuseMap;
uniform sampler2D normalMap;
uniform sampler2D specularMap;
uniform samplerCubeShadow shadowMap;
varying vec2 TexCoord;
varying vec4 ShadowCoord; // interpolated position in light space
varying vec3 tbnDirToLight; // direction from fragment to light in tangent space
varying vec3 tbnDirToEye;
void main()
{
float shadow = texture( shadowMap, -ShadowCoord );
vec3 n = normalize( texture2D( normalMap, TexCoord.st ).rgb * 2.0 - 1.0 );
vec3 L = normalize( tbnDirToLight );
vec3 E = normalize( tbnDirToEye );
float diffuse = max(dot(n,L), 0.0) * 2.0;
float specular = max( pow( dot( reflect( -L, n ), E ), 32.0 ) * 8.0, 0.0 );
vec4 d = texture2D( diffuseMap, TexCoord );
vec4 s = texture2D( specularMap, TexCoord );
gl_FragColor = (shadow * (d*diffuse + s*specular) * gl_LightSource[0].diffuse * att);
}
Also, I’d like to using nothing but forward compatible stuff. I’ve having a hard time distinguishing but I’m pretty sure there’s old stuff in this code.