/// <summary>
/// Casts a real time 3D shadow.
/// </summary>
/// <param name="gl">The OpenGL object.</param>
/// <param name="lights">The lights.</param>
private void CastShadow(OpenGL gl)
{
// Set the connectivity, (calculate the neighbours of each face).
SetConnectivity();
// Get the lights in the scene.
var lights = TraverseToRootElement().Traverse <Light>(l => l.IsEnabled && l.On && l.CastShadow);
// Get some useful references.
var faces = ParentPolygon.Faces;
// Go through every light in the scene.
foreach (var light in lights)
{
// Every face will have a visibility setting.
bool[] facesVisible = new bool[faces.Count];
// Get the light position relative to the polygon.
Vertex lightPos = light.Position;
lightPos = lightPos - ParentPolygon.Transformation.TranslationVertex;
// Go through every face, finding out whether it's visible to the light.
for (int nFace = 0; nFace < faces.Count; nFace++)
{
// Get a reference to the face.
Face face = faces[nFace];
// Is this face facing the light?
float[] planeEquation = face.GetPlaneEquation(ParentPolygon);
float side = planeEquation[0] * lightPos.X +
planeEquation[1] * lightPos.Y +
planeEquation[2] * lightPos.Z + planeEquation[3];
facesVisible[nFace] = (side > 0) ? true : false;
}
// Save all the attributes.
gl.PushAttrib(OpenGL.GL_ALL_ATTRIB_BITS);
// Turn off lighting.
gl.Disable(OpenGL.GL_LIGHTING);
// Turn off writing to the depth mask.
gl.DepthMask(0);
gl.DepthFunc(OpenGL.GL_LEQUAL);
// Turn on stencil buffer testing.
gl.Enable(OpenGL.GL_STENCIL_TEST);
// Translate our shadow volumes.
ParentPolygon.PushObjectSpace(gl);
// Don't draw to the color buffer.
gl.ColorMask(0, 0, 0, 0);
gl.StencilFunc(OpenGL.GL_ALWAYS, 1, 0xFFFFFFFF);
gl.Enable(OpenGL.GL_CULL_FACE);
// First Pass. Increase Stencil Value In The Shadow
gl.FrontFace(OpenGL.GL_CCW);
gl.StencilOp(OpenGL.GL_KEEP, OpenGL.GL_KEEP, OpenGL.GL_INCR);
DoShadowPass(gl, lightPos, facesVisible);
// Second Pass. Decrease Stencil Value In The Shadow
gl.FrontFace(OpenGL.GL_CW);
gl.StencilOp(OpenGL.GL_KEEP, OpenGL.GL_KEEP, OpenGL.GL_DECR);
DoShadowPass(gl, lightPos, facesVisible);
gl.FrontFace(OpenGL.GL_CCW);
ParentPolygon.PopObjectSpace(gl);
// Enable writing to the color buffer.
gl.ColorMask(1, 1, 1, 1);
// Draw A Shadowing Rectangle Covering The Entire Screen
gl.Color(light.ShadowColor);
gl.Enable(OpenGL.GL_BLEND);
gl.BlendFunc(OpenGL.GL_SRC_ALPHA, OpenGL.GL_ONE_MINUS_SRC_ALPHA);
gl.StencilFunc(OpenGL.GL_NOTEQUAL, 0, 0xFFFFFFF);
gl.StencilOp(OpenGL.GL_KEEP, OpenGL.GL_KEEP, OpenGL.GL_KEEP);
Quadrics.Sphere shadow = new Quadrics.Sphere();
shadow.Transformation.ScaleX = shadowSize;
shadow.Transformation.ScaleY = shadowSize;
shadow.Transformation.ScaleZ = shadowSize;
shadow.Render(gl, RenderMode.Design);
gl.PopAttrib();
}
}
/// <summary>
/// Casts a real time 3D shadow.
/// </summary>
/// <param name="gl">The OpenGL object.</param>
/// <param name="lights">The lights.</param>
private void CastShadow(OpenGL gl)
{
// Set the connectivity, (calculate the neighbours of each face).
SetConnectivity();
// Get the lights in the scene.
var lights = TraverseToRootElement().Traverse<Light>(l => l.IsEnabled && l.On && l.CastShadow);
// Get some useful references.
var faces = ParentPolygon.Faces;
// Go through every light in the scene.
foreach(var light in lights)
{
// Every face will have a visibility setting.
bool[] facesVisible = new bool[faces.Count];
// Get the light position relative to the polygon.
Vertex lightPos = light.Position;
lightPos = lightPos - ParentPolygon.Transformation.TranslationVertex;
// Go through every face, finding out whether it's visible to the light.
for(int nFace = 0; nFace < faces.Count; nFace++)
{
// Get a reference to the face.
Face face = faces[nFace];
// Is this face facing the light?
float[] planeEquation = face.GetPlaneEquation(ParentPolygon);
float side = planeEquation[0] * lightPos.X +
planeEquation[1] * lightPos.Y +
planeEquation[2] * lightPos.Z + planeEquation[3];
facesVisible[nFace] = (side > 0) ? true : false;
}
// Save all the attributes.
gl.PushAttrib(OpenGL.GL_ALL_ATTRIB_BITS);
// Turn off lighting.
gl.Disable(OpenGL.GL_LIGHTING);
// Turn off writing to the depth mask.
gl.DepthMask(0);
gl.DepthFunc(OpenGL.GL_LEQUAL);
// Turn on stencil buffer testing.
gl.Enable(OpenGL.GL_STENCIL_TEST);
// Translate our shadow volumes.
ParentPolygon.PushObjectSpace(gl);
// Don't draw to the color buffer.
gl.ColorMask(0, 0, 0, 0);
gl.StencilFunc(OpenGL.GL_ALWAYS, 1, 0xFFFFFFFF);
gl.Enable(OpenGL.GL_CULL_FACE);
// First Pass. Increase Stencil Value In The Shadow
gl.FrontFace(OpenGL.GL_CCW);
gl.StencilOp(OpenGL.GL_KEEP, OpenGL.GL_KEEP, OpenGL.GL_INCR);
DoShadowPass(gl, lightPos, facesVisible);
// Second Pass. Decrease Stencil Value In The Shadow
gl.FrontFace(OpenGL.GL_CW);
gl.StencilOp(OpenGL.GL_KEEP, OpenGL.GL_KEEP, OpenGL.GL_DECR);
DoShadowPass(gl, lightPos, facesVisible);
gl.FrontFace(OpenGL.GL_CCW);
ParentPolygon.PopObjectSpace(gl);
// Enable writing to the color buffer.
gl.ColorMask(1, 1, 1, 1);
// Draw A Shadowing Rectangle Covering The Entire Screen
gl.Color(light.ShadowColor);
gl.Enable(OpenGL.GL_BLEND);
gl.BlendFunc(OpenGL.GL_SRC_ALPHA, OpenGL.GL_ONE_MINUS_SRC_ALPHA);
gl.StencilFunc(OpenGL.GL_NOTEQUAL, 0, 0xFFFFFFF);
gl.StencilOp(OpenGL.GL_KEEP, OpenGL.GL_KEEP, OpenGL.GL_KEEP);
Quadrics.Sphere shadow = new Quadrics.Sphere();
shadow.Transformation.ScaleX = shadowSize;
shadow.Transformation.ScaleY = shadowSize;
shadow.Transformation.ScaleZ = shadowSize;
shadow.Render(gl, RenderMode.Design);
gl.PopAttrib();
}
}
