/// <summary>
/// Render the current scene. The culling will be performed inside this method,
/// because we need all meshes here to compute the shadow maps.
/// </summary>
/// <param name="camera">Current camera</param>
/// <param name="visibleLights"></param>
/// <param name="meshes">All meshes</param>
/// <param name="sceneGraph"></param>
/// <param name="particleSystems"></param>
/// <param name="gameTime"></param>
/// <param name="lights">Visible lights</param>
/// <returns></returns>
public RenderTarget2D RenderScene(Camera camera, BaseSceneGraph sceneGraph)
{
InstancingGroupManager.Reset();
sceneGraph.DoPreFrameWork(camera.Frustum);
_depthDownsampledThisFrame = false;
_currentCamera = camera;
//compute the frustum corners for this camera
ComputeFrustumCorners(camera);
//this resets the free shadow maps
_shadowRenderer.InitFrame();
_visibleLights.Clear();
sceneGraph.GetVisibleLights(camera.Frustum, _visibleLights);
//sort lights, choose the shadow casters
BuildLightEntries(camera);
SelectShadowCasters();
//generate all shadow maps
GenerateShadows(camera, sceneGraph);
//first of all, we must bind our GBuffer and reset all states
GraphicsDevice.SetRenderTargets(_gBufferBinding);
GraphicsDevice.Clear(ClearOptions.DepthBuffer | ClearOptions.Stencil, Color.Black, 1.0f, 0);
GraphicsDevice.BlendState = BlendState.Opaque;
GraphicsDevice.DepthStencilState = DepthStencilState.None;
GraphicsDevice.RasterizerState = RasterizerState.CullNone;
//bind the effect that outputs the default GBuffer values
_clearGBuffer.CurrentTechnique.Passes[0].Apply();
//draw a full screen quad for clearing our GBuffer
_quadRenderer.RenderQuad(GraphicsDevice, -Vector2.One, Vector2.One);
GraphicsDevice.DepthStencilState = DepthStencilState.Default;
GraphicsDevice.RasterizerState = RasterizerState.CullCounterClockwise;
//select the visible meshes
CullVisibleMeshes(camera, sceneGraph);
//now, render them to the G-Buffer
RenderToGbuffer(camera);
//resolve our GBuffer and render the lights
//clear the light buffer with black
GraphicsDevice.SetRenderTargets(_lightAccumBinding);
//dont be fooled by Color.Black, as its alpha is 255 (or 1.0f)
GraphicsDevice.Clear(new Color(0, 0, 0, 0));
//dont use depth/stencil test...we dont have a depth buffer, anyway
GraphicsDevice.DepthStencilState = DepthStencilState.None;
GraphicsDevice.RasterizerState = RasterizerState.CullCounterClockwise;
//draw using additive blending.
//At first I was using BlendState.additive, but it seems to use alpha channel for modulation,
//and as we use alpha channel as the specular intensity, we have to create our own blend state here
GraphicsDevice.BlendState = _lightAddBlendState;
RenderLights(camera);
//reconstruct each object shading, using the light texture as input (and another specific parameters too)
GraphicsDevice.SetRenderTarget(_outputTexture);
GraphicsDevice.Clear(ClearOptions.DepthBuffer | ClearOptions.Stencil | ClearOptions.Target, Color.Black, 1.0f, 0);
GraphicsDevice.DepthStencilState = DepthStencilState.Default;
GraphicsDevice.BlendState = BlendState.Opaque;
GraphicsDevice.RasterizerState = RasterizerState.CullCounterClockwise;
//reconstruct the shading, using the already culled list
ReconstructShading(camera);
//render objects that doesn't need the lightbuffer information, such as skyboxes, pure reflective meshes, etc
DrawOpaqueObjects(camera);
//draw objects with transparency
DrawBlendObjects(camera);
//draw SSAO texture. It's not correct to do it here, because ideally the SSAO should affect only
//the ambient light, but it looks good this way
//unbind our final buffer and return it
GraphicsDevice.SetRenderTarget(null);
return(_outputTexture);
}
