/// <summary>
///
/// </summary>
/// <param name="sceneNodeBase"></param>
/// <param name="arg"></param>
static void Extrude(SceneNodeBase sceneNodeBase, ShadowVolumeExtrudeEventArgs arg)
{
if (sceneNodeBase != null)
{
var node = sceneNodeBase as ISupportShadowVolume;
TwoFlags flags = (node != null) ? node.EnableShadowVolume : TwoFlags.None;
bool before = (node != null) && ((flags & TwoFlags.BeforeChildren) == TwoFlags.BeforeChildren);
bool children = (node == null) || ((flags & TwoFlags.Children) == TwoFlags.Children);
if (before)
{
flags = node.EnableExtrude;
before = (flags & TwoFlags.BeforeChildren) == TwoFlags.BeforeChildren;
}
if (children)
{
flags = (node != null) ? node.EnableExtrude : TwoFlags.None;
children = (node == null) || ((flags & TwoFlags.Children) == TwoFlags.Children);
}
if (before)
{
node.ExtrudeShadow(arg);
}
if (children)
{
foreach (var item in sceneNodeBase.Children)
{
Extrude(item, arg);
}
}
}
}
/// <summary>
///
/// </summary>
/// <param name="param"></param>
public override void Act(ActionParams param)
{
Scene scene = this.scene;
bool displayShadowVolume = this.DisplayShadowVolume;
this.depthClamp.On();// for infinite back cap of shadow volumes.
// Render depth info into depth buffer and ambient color into color buffer.
{
var arg = new ShadowVolumeAmbientEventArgs(param, scene.Camera, scene.AmbientColor);
RenderAmbientColor(scene.RootNode, arg);
}
this.stencilTest.On(); // enable stencil test.
foreach (var light in scene.Lights)
{
// Clear stencil buffer.
{
GL.Instance.Clear(GL.GL_STENCIL_BUFFER_BIT); // this seems not working.
// do the same thing.
this.depthTest.On(); // Disable depth test to make sure this node works for every stencil point.
this.depthMask.On(); // Disable writing to depth buffer.
this.clearStencilNode.RenderBeforeChildren(null); // this helps clear stencil buffer because `glClear(GL_STENCIL_BUFFER_BIT);` doesn't work on my laptop.
this.depthMask.Off();
this.depthTest.Off();
}
// Extrude shadow volume and save shadow info into stencil buffer.
{
this.depthMask.On(); // Disable writing to depth buffer.
if (!displayShadowVolume)
{
this.colorMask.On();
} // Disable writing to color buffer.
else
{
this.polygonMode.On(); this.lineSipple.On();
}
this.cullFace.On(); // Disable culling face.
GL.Instance.StencilFunc(GL.GL_ALWAYS, 0, 0xFF); // always pass stencil test.
// If depth test fails for back face, increase value in stencil buffer.
glStencilOpSeparate(GL.GL_BACK, GL.GL_KEEP, GL.GL_INCR_WRAP, GL.GL_KEEP);
// If depth test fails for front face, decrease value in stencil buffer.
glStencilOpSeparate(GL.GL_FRONT, GL.GL_KEEP, GL.GL_DECR_WRAP, GL.GL_KEEP);
// Extrude shadow volume. And shadow info will be saved into stencil buffer automatically according to `glStencilOp...`.
var arg = new ShadowVolumeExtrudeEventArgs(param, scene.Camera, light);
Extrude(scene.RootNode, arg);
this.cullFace.Off();
if (!displayShadowVolume)
{
this.colorMask.Off();
}
else
{
this.polygonMode.Off(); this.lineSipple.Off();
}
this.depthMask.Off();
}
//
{
// Draw only if the corresponding stencil value is zero.
GL.Instance.StencilFunc(GL.GL_EQUAL, 0x0, 0xFF);
// prevent updating to the stencil buffer.
GL.Instance.StencilOp(GL.GL_KEEP, GL.GL_KEEP, GL.GL_KEEP);
this.blend.On(); // add illuminated color to ambient color.
// light the scene up.
var arg = new ShadowVolumeUnderLightEventArgs(param, scene.Camera, light);
RenderUnderLight(scene.RootNode, arg);
this.blend.Off();
}
}
this.stencilTest.Off();
this.depthClamp.Off();
}