/// <summary>
/// Update shadow map.
/// </summary>
/// <param name="ctx">
/// A <see cref="GraphicsContext"/> used for allocating resources.
/// </param>
public override void UpdateShadowMap(GraphicsContext ctx, SceneGraph shadowGraph)
{
CheckCurrentContext(ctx);
if (shadowGraph == null)
{
throw new ArgumentNullException("shadowGraph");
}
// Compute light matrix
IModelMatrix viewMatrix = new ModelMatrix(); // LocalModel.Multiply(LightMatrix.GetInverseMatrix()).GetInverseMatrix();
viewMatrix.LookAtDirection((Vertex3d)LocalModel.Position, (Vertex3f)Direction, Vertex3d.UnitY);
// Set light scene view
shadowGraph.ProjectionMatrix = new PerspectiveProjectionMatrix(FalloffAngle * 2.0f, 1.0f, 0.1f, 100.0f);
shadowGraph.ViewMatrix = viewMatrix;
_ShadowFramebuffer.BindDraw(ctx);
// Reset viewport
new ViewportState(0, 0, (int)_ShadowMap.Width, (int)_ShadowMap.Height).Apply(ctx, null);
_ShadowFramebuffer.Clear(ctx, ClearBufferMask.DepthBufferBit);
shadowGraph.Draw(ctx, _ShadowProgram);
_ShadowFramebuffer.UnbindDraw(ctx);
// Cache view matrix
_ShadowViewMatrix = _BiasMatrix.Multiply(shadowGraph.ProjectionMatrix.Multiply(viewMatrix));
}