Okay, so I decided to use FBOs instead since that problem seems to have been indeed me rendering onto the back framebuffer immediately. And having switched to FBOs I can actually see the shadowmap when I map it onto a quad (it's faint but it's visible at least). However, my problems don't end there: now the entire scene is black (except for the textured quad and brownish glClearColor() defined background). I'm guessing my texture coordinate generation is wrong but not sure. Any help would be greatly appreciated!
new init:
glGenTextures(1, &shadowmap_);
glBindTexture(GL_TEXTURE_2D, shadowmap_);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, 512, 512, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, NULL);
//glGenRenderbuffers(1, &renderbuffer_);
//glBindRenderbuffer(GL_RENDERBUFFER, renderbuffer_);
//glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, 512, 512);
glGenFramebuffers(1, &framebuffer_);
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer_);
//glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, renderbuffer_);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, shadowmap_, 0);
new render:
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer_);
//glDrawBuffer(GL_NONE);
//glReadBuffer(GL_NONE);
glClearColor(0.5, 0.2, 0.1, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// position the light
glLightfv(GL_LIGHT0, GL_POSITION, lightPos_);
// set up the projection parameters from the light's POV
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
gluPerspective(lightFOV_, lightAspect_, lightNear_, lightFar_);
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
// translate to the light's position
gluLookAt(lightPos_[0], lightPos_[1], lightPos_[2], -1.0f, 0.0f, 5.0f, 0.0f, 1.0f, 0.0f);
// render the scene to get the depth information
renderSceneElements();
glPopMatrix();
// end the projection modification
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
glBindFramebuffer(GL_FRAMEBUFFER, 0);
// copy over the depth information
//glBindTexture(GL_TEXTURE_2D, shadowmap_);
//glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, 512, 512);
// matrix defining the planes for S, Q, R, T components for texture generation
float planeMatrix[16];
glPushMatrix();
glLoadIdentity();
// compensate for the eye-coordinate to texture coordinate conversion: [-1,1] to [0,1]
glTranslatef(0.5f, 0.5f, 0.0f);
glScalef(0.5f, 0.5f, 1.0f);
// do the perspective projection and translate to the light's position
gluPerspective(lightFOV_, lightAspect_, lightNear_, lightFar_);
gluLookAt(lightPos_[0], lightPos_[1], lightPos_[2], -1.0f, 0.0f, 5.0f, 0.0f, 1.0f, 0.0f);
glGetFloatv(GL_MODELVIEW_MATRIX, planeMatrix);
glPopMatrix();
// go from OpenGL's column-major to row-major matrix form
transposeMatrix16(planeMatrix);
// set up the type for texture generation
glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
glTexGeni(GL_R, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
glTexGeni(GL_Q, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);
// data for texture generation
glTexGenfv(GL_S, GL_OBJECT_PLANE, &planeMatrix[0]);
glTexGenfv(GL_T, GL_OBJECT_PLANE, &planeMatrix[4]);
glTexGenfv(GL_R, GL_OBJECT_PLANE, &planeMatrix[8]);
glTexGenfv(GL_Q, GL_OBJECT_PLANE, &planeMatrix[12]);
glEnable(GL_TEXTURE_GEN_S);
glEnable(GL_TEXTURE_GEN_T);
glEnable(GL_TEXTURE_GEN_R);
glEnable(GL_TEXTURE_GEN_Q);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, shadowmap_);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_FUNC, GL_LEQUAL);
glTexParameteri(GL_TEXTURE_2D, GL_DEPTH_TEXTURE_MODE, GL_LUMINANCE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_COMPARE_R_TO_TEXTURE);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
renderSceneElements();
glDisable(GL_LIGHTING);
glDisable(GL_LIGHT0);
glDisable(GL_TEXTURE_2D);
glDisable(GL_TEXTURE_GEN_Q);
glDisable(GL_TEXTURE_GEN_R);
glDisable(GL_TEXTURE_GEN_T);
glDisable(GL_TEXTURE_GEN_S);
glPushMatrix();
glEnable(GL_TEXTURE_2D);
//glBindTexture(GL_TEXTURE_2D, shadowmap_);
glTexParameteri(GL_TEXTURE_2D, GL_DEPTH_TEXTURE_MODE, GL_NONE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_NONE);
glTranslatef(3.0f, 2.0f, 5.0f);
glBegin(GL_QUADS);
glTexCoord2f(0.0f, 0.0f);
glVertex3f(0.0f, 0.0f, 0.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex3f(3.0f, 0.0f, 0.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex3f(3.0f, 3.0f, 0.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex3f(0.0f, 3.0f, 0.0f);
glEnd();
glDisable(GL_TEXTURE_2D);
glPopMatrix();
Note that I had to explicitly bind the texture - I thought it would be automatically related to the framebuffer and hence enabling texturing would have caused that texture to be used? If I don't have that binding there, OpenGL selects my previously used texture.
Thanks in advance!
EDIT: After searching on Google for the millionth time, I ran into someone's post stating that glTexGen works only with specific objects, ie OpenGL wouldn't generate proper coordinates for quads/cubes. Now I knew that before but for whatever reason hadn't considered it until now. The OpenGL Red Book doesn't clarify it either and the given code there is really awkward. I've matched most of my code with the stuff in the book but I'm not really sure about the glTexGen stuff... If I have the shadowmap then how do I map it onto the scene?
