I'm having trouble with any form of shader at the moment, it seems I get weird artefacts when I move around,
And this happens with any form of shader so I'm wondering whether there is a problem with my matrices or in the way I'm using them.
I should also mention if I slip someone else's shader in for Shadow Volumes/Shadow Mapping it also does the same thing, yet works perfectly in their respective projects.
I'm following the good ol' Open GL Shading Language as a guide but its not helping I'm finding. The following is someone else's shader which works fine in their project, but not mine so I am wondering what could be the problem (obviously my code doesn't work :P)
uniform vec3 uLightPos;
#define EXTRUSION_FACTOR 100.0
void main()
{
vec4 Position = gl_Vertex;
vec3 LightDir = normalize(uLightPos - Position.xyz);
float DiffuseLight = max(dot(gl_Normal, LightDir), 0.0);
//Check if the vertex is facing the light.
if(DiffuseLight <= 0.0)
{
//Extrude!
Position = Position + (Position - vec4(uLightPos, 1.0)) * EXTRUSION_FACTOR;
//Place the extruded vector at infinity.
Position.w = 0.0;
}
//Transform position to clip space.
gl_Position = ftransform();
}
My Shader Algorithm:
void JShadowVolumeShaderAlgorithm::render(GLfloat x, GLfloat y, GLfloat z) {
//Save all attributes.
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, 1.0f, 0.1f, 1000.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
scene->updateCameraView();
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
int noOfLights = scene->getLightManager()->getNumberOfLightsUsed();
//JModelManager * modelManager = scene->getModelManager();
//for each light
for(int i = 0; i < noOfLights ; i++) {
JVector3D lightPos = scene->getLightManager()->getLight(i)->getPosition();
GLfloat lPos [4] = {lightPos.x, lightPos.y, lightPos.z, 1.0};
glLightfv(GL_LIGHT0, GL_POSITION, lPos);
//Fill the depth buffer.
glDisable(GL_LIGHTING);
scene->renderInternalProperties();
scene->renderSceneModels();
//Prevents z-fighting.
if (clipPlaneBehindLight) {
glEnable(GL_POLYGON_OFFSET_FILL);
//glPolygonOffset(0.0f, 100.0f);
glPolygonOffset(bias, offset);
}
glDepthMask(GL_FALSE);
glDepthFunc(GL_LESS);
glEnable(GL_STENCIL_TEST);
glEnable(GL_STENCIL_TEST_TWO_SIDE_EXT); //Use the two side stencil buffer.
glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glActiveStencilFaceEXT(GL_FRONT);
glStencilOp(GL_KEEP, GL_INCR_WRAP_EXT, GL_KEEP);
glStencilFunc(GL_ALWAYS, 0, 0);
//Decrement the stencil buffer.
glActiveStencilFaceEXT(GL_BACK);
glStencilOp(GL_KEEP, GL_DECR_WRAP_EXT, GL_KEEP);
glStencilFunc(GL_ALWAYS, 0, 0);
vp->Use();
glUniform3fARB(m_glslLightPos, lightPos.x, lightPos.y, lightPos.z);
scene->renderSceneModels();
vp->Disable();
glDisable(GL_POLYGON_OFFSET_FILL);
glDepthFunc(GL_LEQUAL);
glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
glActiveStencilFaceEXT(GL_FRONT);
glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
glStencilFunc(GL_EQUAL, 0, 0xFFFFFFFF);
glActiveStencilFaceEXT(GL_BACK);
glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
glStencilFunc(GL_EQUAL, 0, 0xFFFFFFFF);
//The light pass.
glEnable(GL_LIGHTING);
scene->renderInternalProperties();
scene->renderSceneModels();
glDisable(GL_BLEND);
}
}
I'm wondering whether its something to do with incorrect normals, but can't be sure.
Neutrinohunter
