C# OpenGL.StencilFunc方法代码示例

 /// <summary>
 /// Sets the attributes.
 /// </summary>
 /// <param name="gl">The OpenGL instance.</param>
 public override void SetAttributes(OpenGL gl)
 {
     if (enableStencilTest.HasValue) gl.EnableIf(OpenGL.GL_STENCIL_TEST, enableStencilTest.Value);
     if (stencilFunction.HasValue && stencilReference.HasValue && stencilMask.HasValue) 
         gl.StencilFunc(stencilFunction.Value, stencilReference.Value, stencilMask.Value);
     if (stencilClearIndex.HasValue) gl.ClearStencil(stencilClearIndex.Value);
     if (stencilWriteMask.HasValue) gl.StencilMask(stencilWriteMask.Value);
     if (operationFail.HasValue && operationDepthFail.HasValue && operationDepthPass.HasValue)
         gl.StencilOp(operationFail.Value, operationDepthFail.Value, operationDepthPass.Value);
     
 }

        /// <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="light">The source light.</param>
        public void CastShadow(OpenGL gl, Collections.LightCollection lights)
        {
            //	Set the connectivity, (calculate the neighbours of each face).
            SetConnectivity();

            //	Go through every light in the scene.
            foreach(Lights.Light light in lights)
            {
                //	Skip null lights.
                if(light == null)
                    continue;

                //	Skip turned off lights and non shadow lights.
                if(light.On == false || light.CastShadow == false)
                    continue;

                //	Every face will have a visibility setting.
                bool[] facesVisible = new bool[faces.Count];

                //	Get the light position relative to the polygon.
                Vertex lightPos = light.Translate;
                lightPos = lightPos - Translate;

                //	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(this);
                    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.ALL_ATTRIB_BITS);

                //	Turn off lighting.
                gl.Disable(OpenGL.LIGHTING);

                //	Turn off writing to the depth mask.
                gl.DepthMask(0);
                gl.DepthFunc(OpenGL.LEQUAL);

                //	Turn on stencil buffer testing.
                gl.Enable(OpenGL.STENCIL_TEST);

                //	Translate our shadow volumes.
                gl.PushMatrix();
                Transform(gl);

                //	Don't draw to the color buffer.
                gl.ColorMask(0, 0, 0, 0);
                gl.StencilFunc(OpenGL.ALWAYS, 1, 0xFFFFFFFF);

                gl.Enable(OpenGL.CULL_FACE);

                //	First Pass. Increase Stencil Value In The Shadow
                gl.FrontFace(OpenGL.CCW);
                gl.StencilOp(OpenGL.KEEP, OpenGL.KEEP, OpenGL.INCR);
                DoShadowPass(gl, lightPos, facesVisible);

                //	Second Pass. Decrease Stencil Value In The Shadow
                gl.FrontFace(OpenGL.CW);
                gl.StencilOp(OpenGL.KEEP, OpenGL.KEEP, OpenGL.DECR);
                DoShadowPass(gl, lightPos, facesVisible);

                gl.FrontFace(OpenGL.CCW);

                gl.PopMatrix();

                //	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.BLEND);
                gl.BlendFunc(OpenGL.SRC_ALPHA, OpenGL.ONE_MINUS_SRC_ALPHA);
                gl.StencilFunc(OpenGL.NOTEQUAL, 0, 0xFFFFFFF);
                gl.StencilOp(OpenGL.KEEP, OpenGL.KEEP, OpenGL.KEEP);

                Quadrics.Sphere shadow = new Quadrics.Sphere();
                shadow.Scale.Set(shadowSize, shadowSize, shadowSize);
                shadow.Draw(gl);

                gl.PopAttrib();
            }
        }