Only one object rendered to FBO for Shadow Map

Question

I've been playing around with rendering shadow maps using FBOs in OpenGL. I set up a simple directional light in my engine and managed to get a shadow map rendered. My Scene is a big castle and the shadow was cast over most of the other objects in the scene. Out of curiosity I removed the castle and just added a simple floor and my shadow map no longer renders properly. It seems that only one object at a time is making it through my render pass and onto the shadow map.

Here's an overview of the way the render is structured:

void RenderingManager::RenderGL()
{
    PreRenderGL();

    ShadowPassGL();

    //Other user defined render passes here?

    ScenePassGL();

    //Cleanup
    directionalLights.clear();
    pointLights.clear();
    renderables.clear();
}

The ShadowPassGL() call is fairly simple

void RenderingManager::ShadowPassGL()
{
    glViewport(0, 0, 1024, 1024);
    for (unsigned int i = 0; i < directionalLights.size(); i++)
        directionalLights[i]->RenderShadowMap(ShadowShader);
}

The RenderShadowMap(Shader* shadowShader) call is a bit more complicated but it seems the orthographic view is setup properly, the look at view is also correct. I have verified that the matrices that are generated by my math functions work.

void DirectionalLightInternal::RenderShadowMapGL(Shader* shadowShader)
{
    //Bind shadow shader for rendering shadow maps
    shadowShader->bindShader();

    //Send info about the directional light to the shader for shadow mapping
    Vector3 focalPoint = direction * -10;

    //Compute MVP from light's direction
    Matrix4 depthProjection = Matrix4::getOrthographicProjection(-10, 10, -10, 10, -20, 20);
    Matrix4 depthView = Matrix4::getLookAtView(focalPoint, Vector3(0, 0, 0), Vector3(0, 1, 0));

    depthMVP = depthView * depthProjection;

    shadowShader->setGlobalMatrix4("depthMVP", depthMVP);

    //Actually bind framebuffer and render shadow map for texture

    //Bind buffer for drawing
    glBindFramebuffer(GL_FRAMEBUFFER, shadowBuffer);

    glClearDepth(1.0f);
    glClear(GL_DEPTH_BUFFER_BIT);

    //render buffer
    RenderingManager::RenderPass();

    //Clean up
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    shadowShader->freeShader();
}

And the final bit of code that I think is relevant is the RenderPass() method which just loops through all renderable objects and tries to render them with RenderObjectGL(Renderable renderable).

void RenderingManager::RenderObjectGL(Renderable renderable)
{
        Mesh* mesh = renderable.mesh;

        GLint shaderProgram;
        glGetIntegerv(GL_CURRENT_PROGRAM, &shaderProgram);

        GLuint vPosition = glGetAttribLocation(shaderProgram, "vPosition");
        GLuint vNormal = glGetAttribLocation(shaderProgram, "vNormal");
        GLuint vTexCoord = glGetAttribLocation(shaderProgram, "vTexCoord");

        glEnableVertexAttribArray(vPosition);
        glEnableVertexAttribArray(vNormal);
        glEnableVertexAttribArray(vTexCoord);

        int normalOffset = mesh->getPointSize();
        int texCoordOffset = normalOffset + mesh->getNormalSize();

        glBindBuffer(GL_ARRAY_BUFFER, mesh->getVBO());
        glVertexAttribPointer(vPosition, 3, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
        glVertexAttribPointer(vNormal, 3, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(normalOffset));
        glVertexAttribPointer(vTexCoord, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(texCoordOffset));

        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, mesh->getIBO());

        //Draw Shape
        glDrawElements(GL_TRIANGLES, mesh->getNumberOfVerts(), GL_UNSIGNED_SHORT, (void *)0);
}

//Render every object in the scene; assume a bound shader
void RenderingManager::RenderPassGL()
{
    for(unsigned int i = 0; i < renderables.size(); i++)
        RenderObjectGL(renderables[i]);
}

I figured some images to illustrate the problem would be pretty useful.

When I render with the castle it looks like this:

And the shadow map from the scene is:

Interestingly the shadow map is really just of the castle, the other objects aren't in the shadow map.

Now the scene with just the floor:

And its shadow map:

Which again seems to be of just the floor, none of the other objects in my scene. Is there some aspect of FBOs that I'm missing here?

Answer 1

After much deliberation and a stroke of insight I figured out what the problem was. It was a problem with my shadow map vertex shader; I wasn't putting the objects into model space. That means that all objects were being rendered at 0, 0, 0 with a scale of 1 and no rotation. OOPS.

Properly applying a model matrix in the shader managed to fix the issue.

EDIT: If you're interested in seeing the exact code that fixed the problem here's a link to the commit on Github: https://github.com/Honeybunch/Brickware-Engine/commit/4908040f3223ae157cdb55244bc6e079f7970327

There was some extra architecture that went into getting the model matrix sent to the shadow shader that might be interesting.