C# OpenGL.BlendFunc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(enableAlphaTest.HasValue && alphaTestFunction.HasValue && alphaTestReferenceValue.HasValue) 
            {
                gl.EnableIf(OpenGL.GL_ALPHA_TEST, enableAlphaTest.Value);
                gl.AlphaFunc(alphaTestFunction.Value, alphaTestReferenceValue.Value);
            }
            
            if(enableBlend.HasValue && blendingSourceFactor.HasValue && blendingDestinationFactor.HasValue) 
            {
                gl.EnableIf(OpenGL.GL_BLEND, enableBlend.Value);
                gl.BlendFunc(blendingSourceFactor.Value, blendingDestinationFactor.Value);
            }

            if(enableDither.HasValue) gl.EnableIf(OpenGL.GL_DITHER, enableDither.Value);
            if(drawBufferMode.HasValue) gl.DrawBuffer(drawBufferMode.Value);
            
            if(enableLogicOp.HasValue && logicOp.HasValue) 
            {
                gl.EnableIf(OpenGL.GL_COLOR_LOGIC_OP, enableLogicOp.Value);
                gl.LogicOp(logicOp.Value);
            }
            if(colorModeClearColor != null) gl.ClearColor(colorModeClearColor.R, colorModeClearColor.G, colorModeClearColor.B, colorModeClearColor.A);
            //todowritemask
        }

 /// <summary>
 /// Initialises the supplied OpenGL instance for high quality rendering.
 /// </summary>
 /// <param name="gl">The OpenGL instance.</param>
 public static void InitialiseHighQuality(OpenGL gl)
 {
     //	Set parameters that give us some high quality settings.
     gl.Enable(OpenGL.GL_DEPTH_TEST);
     gl.Enable(OpenGL.GL_NORMALIZE);
     gl.Enable(OpenGL.GL_LIGHTING);
     gl.Enable(OpenGL.GL_TEXTURE_2D);
     gl.ShadeModel(OpenGL.GL_SMOOTH);
     gl.LightModel(OpenGL.GL_LIGHT_MODEL_TWO_SIDE, OpenGL.GL_TRUE);
     gl.Enable(OpenGL.GL_BLEND);
     gl.BlendFunc(OpenGL.GL_SRC_ALPHA, OpenGL.GL_ONE_MINUS_SRC_ALPHA);
 }

        public virtual void DrawGrid(OpenGL gl)
        {
            gl.PushAttrib(OpenGL.LINE_BIT | OpenGL.ENABLE_BIT | OpenGL.COLOR_BUFFER_BIT);

            //  Turn off lighting, set up some nice anti-aliasing for lines.
            gl.Disable(OpenGL.LIGHTING);
            gl.Hint(OpenGL.LINE_SMOOTH_HINT, OpenGL.NICEST);
            gl.Enable(OpenGL.LINE_SMOOTH);
            gl.Enable(OpenGL.BLEND);
            gl.BlendFunc(OpenGL.SRC_ALPHA, OpenGL.ONE_MINUS_SRC_ALPHA);

            //	Create the grid.
            gl.LineWidth(1.5f);

            gl.Begin(OpenGL.LINES);

                for (int i = -10; i <= 10; i++)
                {
                    gl.Color(0.2f, 0.2f, 0.2f, 1f);
                    gl.Vertex(i, 0, -10);
                    gl.Vertex(i, 0, 10);
                    gl.Vertex(-10, 0, i);
                    gl.Vertex(10, 0, i);
                }

            gl.End();

            //  Turn off the depth test for the axies.
            gl.Disable(OpenGL.DEPTH_TEST);
            gl.LineWidth(2.0f);

            //	Create the axies.
            gl.Begin(OpenGL.LINES);

                gl.Color(1f, 0f, 0f, 1f);
                gl.Vertex(0f, 0f, 0f);
                gl.Vertex(3f, 0f, 0f);
                gl.Color(0f, 1f, 0f, 1f);
                gl.Vertex(0f, 0f, 0f);
                gl.Vertex(0f, 3f, 0f);
                gl.Color(0f, 0f, 1f, 1f);
                gl.Vertex(0f, 0f, 0f);
                gl.Vertex(0f, 0f, 3f);

            gl.End();

            gl.PopAttrib();

               //     gl.Flush();
        }

        /// <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();
            }
        }