I'm trying to set up a simple shadow volume rendering method from which I can expand on. I have implemented shadow mapping but am unpleased with the general results, mainly, I wanted omnidirectional lights. So I did a bunch of reading and found some code but all I'm getting is the scene drawn in grayscale, with no shadows. Here is the code used, it's not very large:
// store current OpenGL state
glPushAttrib(GL_DEPTH_BUFFER_BIT | GL_LIGHTING_BIT | GL_STENCIL_BUFFER_BIT);
// draw the model with the light disabled
glDisable(GL_LIGHTING);
RenderObjects();
glEnable(GL_LIGHTING);
// store current OpenGL state
glPushAttrib(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_POLYGON_BIT | GL_STENCIL_BUFFER_BIT);
glColorMask(0, 0, 0, 0); // do not write to the color buffer
glDepthMask(0); // do not write to the depth (Z) buffer
glEnable(GL_CULL_FACE); // cull faces (back or front)
glEnable(GL_STENCIL_TEST); // enable stencil testing
// set the reference stencil value to 0
glStencilFunc(GL_ALWAYS, 0, ~0);
// increment the stencil value on Z fail
glStencilOp(GL_KEEP, GL_INCR, GL_KEEP);
// draw only the back faces of the shadow volume
glCullFace(GL_FRONT);
// pass in variable
GLOBAL->shadowVolume_extrude->TurnOn();
GLOBAL->shadowVolume_extrude->SetFloat4("lightPosition", GLSL_UNIFORM, lights[0]->position.x, lights[0]->position.y, lights[0]->position.z, 1.0f);
RenderObjects(); // NOT QUITE RIGHT
// decrement the stencil value on Z fail
glStencilOp(GL_KEEP, GL_DECR, GL_KEEP);
// draw only the front faces of the shadow volume
glCullFace(GL_BACK);
RenderObjects(); // NOT QUITE RIGHT
GLOBAL->shadowVolume_extrude->TurnOff();
// restore OpenGL state
glPopAttrib();
// re-draw the model with the light enabled only where
// it has previously been drawn
glDepthFunc(GL_EQUAL);
// update the color only where the stencil value is 0
glEnable(GL_STENCIL_TEST);
glStencilFunc(GL_EQUAL, 0, ~0);
glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
RenderObjects();
// restore OpenGL state
glPopAttrib();
And here is RenderObjects():
void RenderingInterface::RenderObjects(void){
gPHYSICS->DrawShapes(false);
// draw objects, replace this with different rendering techniques switch and call separate functions.
for (unsigned int objectIndex = 0; objectIndex < objectCount; objectIndex++){
Object *current = objects[objectIndex];
for (unsigned int bodyIndex = 0; bodyIndex < current->GetBodyCount(); bodyIndex++){
gGRAPHICS->PushMatrix();
btCollisionObject* colObj = gPHYSICS->GetWorldPtr()->getCollisionObjectArray()[current->GetBody(bodyIndex)->GetBulletCollisionObejctIndex()];
btRigidBody* body = btRigidBody::upcast(colObj);
float m[16];
if (body && body->getMotionState()){
btDefaultMotionState* motionState = (btDefaultMotionState*)body->getMotionState();
motionState->m_graphicsWorldTrans.getOpenGLMatrix(m);
}else{
colObj->getWorldTransform().getOpenGLMatrix(m);
}
gGRAPHICS->MultMatrix(m);
gGRAPHICS->Rotate(90.0f, 1.0f, 0.0f, 0.0f);
gGRAPHICS->Primitive(current->GetBody(bodyIndex)->GetMesh());
gGRAPHICS->PopMatrix();
}
}
}
Just a note, anything using gGRAPHICS-> basically translates directly into opengl
