C# OpenGL.UseProgram方法代碼示例

        private void DrawTrefoilCelShaded(OpenGL gl)
        {
            //  Use the shader program.
            gl.UseProgram(shaderProgram.ProgramObject);

            //  Set the variables for the shader program.
            gl.Uniform3(toonUniforms.DiffuseMaterial, 0f, 0.75f, 0.75f);
            gl.Uniform3(toonUniforms.AmbientMaterial, 0.04f, 0.04f, 0.04f);
            gl.Uniform3(toonUniforms.SpecularMaterial, 0.5f, 0.5f, 0.5f);
            gl.Uniform1(toonUniforms.Shininess, 50f);

            //  Set the light position.
            gl.Uniform3(toonUniforms.LightPosition, 1, new float[4] { 0.25f, 0.25f, 1f, 0f });

            //  Set the matrices.
            gl.UniformMatrix4(toonUniforms.Projection, 1, false, projection.AsColumnMajorArrayFloat);
            gl.UniformMatrix4(toonUniforms.Modelview, 1, false, modelView.AsColumnMajorArrayFloat);
            gl.UniformMatrix3(toonUniforms.NormalMatrix, 1, false, normalMatrix.AsColumnMajorArrayFloat);

            //  Bind the vertex and index buffer.
            gl.BindBuffer(OpenGL.GL_ARRAY_BUFFER, vertexBuffer);
            gl.BindBuffer(OpenGL.GL_ELEMENT_ARRAY_BUFFER, indexBuffer);

            gl.EnableVertexAttribArray(attrPosition);
            gl.EnableVertexAttribArray(attrNormal);

            //  Draw the geometry, straight from the vertex buffer.
            gl.VertexAttribPointer(attrPosition, 3, OpenGL.GL_FLOAT, false, Marshal.SizeOf(typeof(Vertex)), IntPtr.Zero);
            int normalOffset = Marshal.SizeOf(typeof(Vertex));
            gl.VertexAttribPointer(attrNormal, 3, OpenGL.GL_FLOAT, false, Marshal.SizeOf(typeof(Vertex)), IntPtr.Add(new IntPtr(0), normalOffset));

            gl.DrawElements(OpenGL.GL_TRIANGLES, (int)trefoilKnot.IndexCount, OpenGL.GL_UNSIGNED_SHORT, IntPtr.Zero);
        }

        private void runGlThread(object args)
        {
            var inputs = (Tuple<CancellationToken>) args;

            var cancelToken = inputs.Item1;
            var gl = new OpenGL();

            int localRenderWidth = 1;
            int localRenderHeight = 1;
            if (!createRenderContext(gl, localRenderWidth, localRenderHeight))
            {
            //TODO better error handling here
            Console.WriteLine("*** Unable to create OpenGL Render Context");
            return;
            }

            uint activeVaoHandle;
            uint activeGlProgramHandle;
            initGLObjects(gl, out activeVaoHandle, out activeGlProgramHandle);

            ActiveProgramValues localActiveProgramValues = null;
            while (!cancelToken.IsCancellationRequested)
            {
            bool resizeRenderContext;
            lock (this)
            {
                if (!ReferenceEquals(localActiveProgramValues, activeProgramValues))
                {
                    localActiveProgramValues = activeProgramValues;
                    if (localActiveProgramValues.Valid)
                    {
                        linkProgram(gl, localActiveProgramValues, activeGlProgramHandle);
                    } else
                    {
                        // Leave the old program running. This prevents the user from seeing
                        // a black screen while they are in the process of modifying a shader.
                    }
                }

                resizeRenderContext = localRenderWidth != renderWidth || localRenderHeight != renderHeight;
                localRenderWidth = renderWidth;
                localRenderHeight = renderHeight;
            }

            if (resizeRenderContext)
            {
                localActiveProgramValues = null;
                deleteGlObjects(gl, activeVaoHandle, activeGlProgramHandle);
                if (!createRenderContext(gl, localRenderWidth, localRenderHeight))
                {
            //TODO better error handling here
                    Console.WriteLine("*** Unable to resize OpenGL Render Context");
                    return;
                }
                initGLObjects(gl, out activeVaoHandle, out activeGlProgramHandle);
            }

            gl.Clear(OpenGL.GL_COLOR_BUFFER_BIT);
            gl.BindVertexArray(activeVaoHandle);
            gl.UseProgram(activeGlProgramHandle);
            gl.DrawArrays(OpenGL.GL_TRIANGLES, 0, 3);

            // do some other stuff while the image is rendering, to give it a chance to finish
            ShaderCompiler.ValidateShaders(gl);

            var provider = gl.RenderContextProvider as FBORenderContextProvider;
            Debug.Assert(provider != null, "Render context provider is not an FBO renderer");
            //TODO this call to blit will probably block. Find a better way to copy the image to CPU memory.
            gl.Blit(IntPtr.Zero);
            var hBitmap = provider.InternalDIBSection.HBitmap;

            if (hBitmap != IntPtr.Zero)
            {
                var bitmap = GetFormattedBitmapSource(hBitmap);
                // the bitmap needs to be frozen in order to share it between threads
                bitmap.Freeze();
                ImageRendered(bitmap);
            }
            }

            deleteGlObjects(gl, activeVaoHandle, activeGlProgramHandle);
        }

        /// <summary>
        /// Calls glUseProgram(ShaderProgramId) -> invokes executeInProgram-Action -> unbinds program using glUseProgram(0).
        /// </summary>
        /// <param name="gl"></param>
        /// <param name="executeInProgram">The logic to be executed for this shader program.</param>
        public void UseProgram(OpenGL gl, Action executeInProgram)
        {
            // Bind.
            gl.UseProgram(ShaderProgramId);

            // Make sure the program unbinds, even if a problem should occur.
            try
            {
                // Invoke logic.
                executeInProgram.Invoke();
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                // Unbind.
                gl.UseProgram(0);
                ProgramIsBound = false;
            }
        }