/// <summary>
/// Do a frustum culling test on each sub mesh, adding the visible ones to our list
/// </summary>
/// <param name="camera"></param>
/// <param name="meshes"></param>
private void CullVisibleMeshes(Camera camera, BaseSceneGraph sceneGraph)
{
for (int index = 0; index < _visibleMeshes.Length; index++)
{
_visibleMeshes[index].Clear();
}
sceneGraph.GetVisibleMeshes(camera.Frustum, _visibleMeshes);
}
/// <summary>
/// Generate the shadow maps and matrixes for the visible lights. We should limit
/// our shadow-casters based on number of available shadow maps (we could use some
/// performance-related heuristic here too)
/// </summary>
/// <param name="camera"></param>
/// <param name="meshes"></param>
/// <param name="renderWorld"></param>
private void GenerateShadows(Camera camera, BaseSceneGraph sceneGraph)
{
for (int index = 0; index < _lightShadowCasters.Count; index++)
{
LightEntry light = _lightShadowCasters[index];
//only spot
if (light.light.LightType == Light.Type.Spot)
{
_shadowRenderer.GenerateShadowTextureSpotLight(this, sceneGraph, light.light, light.spotShadowMap);
}
}
}
/// <summary>
/// Generate the shadow map for a given spot light
/// </summary>
/// <param name="renderer"></param>
/// <param name="meshes"></param>
/// <param name="light"></param>
/// <param name="shadowMap"></param>
public void GenerateShadowTextureSpotLight(Renderer renderer, BaseSceneGraph renderWorld, Light light, SpotShadowMapEntry shadowMap)
{
//bind the render target
renderer.GraphicsDevice.SetRenderTarget(shadowMap.Texture);
//clear it to white, ie, far far away
renderer.GraphicsDevice.Clear(Color.White);
renderer.GraphicsDevice.BlendState = BlendState.Opaque;
renderer.GraphicsDevice.DepthStencilState = DepthStencilState.Default;
Matrix viewProj = light.ViewProjection;
shadowMap.LightViewProjection = viewProj;
BoundingFrustum frustum = light.Frustum;
_visibleMeshes.Clear();
//cull meshes outside the light volume
renderWorld.GetShadowCasters(frustum, _visibleMeshes);
renderer.InstancingGroupManager.Reset();
for (int index = 0; index < _visibleMeshes.Count; index++)
{
Mesh.SubMesh subMesh = _visibleMeshes[index];
//render it
if (!subMesh.InstanceEnabled)
{
subMesh.RenderShadowMap(ref viewProj, renderer.GraphicsDevice);
}
else
{
renderer.InstancingGroupManager.AddInstancedSubMesh(subMesh);
}
}
renderer.InstancingGroupManager.GenerateInstanceInfo(renderer.GraphicsDevice);
renderer.InstancingGroupManager.RenderShadowMap(ref viewProj, renderer.GraphicsDevice);
}
/// <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);
}
