C# OpenGL.PopMatrix方法代码示例

        public virtual void DrawCircle3D(OpenGL gl)
        {
            gl.PushAttrib(OpenGL.ENABLE_BIT);
            gl.Disable(OpenGL.LIGHTING);

            //	Draw three circles.
            gl.PushMatrix();
            DrawCircle(gl);
            gl.Rotate(90, 1, 0, 0);
            DrawCircle(gl);
            gl.Rotate(90, 0, 0, 1);
            DrawCircle(gl);
            gl.PopMatrix();

            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();
            }
        }

 /// <summary>
 /// Pops the specified parent element.
 /// </summary>
 /// <param name="gl">The OpenGL instance.</param>
 /// <param name="parentElement">The parent element.</param>
 public override void Pop(OpenGL gl, Core.SceneElement parentElement)
 {
     //  Pop the stack.
     gl.PopMatrix();
 }

        /// <summary>
        /// This is always called after drawing, useful to restore the matrix stack etc.
        /// </summary>
        /// <param name="gl"></param>
        protected internal virtual void DoPostDraw(OpenGL gl)
        {
            //	Pop the matrix.
            gl.PopMatrix();

            //  TODO: Display list objects are disabled.
              /*
            //	End the display list (this function only ever gets called
            //	if DoPreDraw returns true).
            gl.EndList();
            modified = false;	//	Back in displaylist country until it changes again.*/
        }