如何向顶点着色器传颜色？

            string vs =
                @"#version 330

                  layout(location = og_positionVertexLocation) in vec4 position;
                  uniform mat4 og_modelViewPerspectiveMatrix;

                  void main()                     
                  {
                        gl_Position = og_modelViewPerspectiveMatrix * position; 
                  }";

            string fs =
                @"#version 330
                 
                  out vec3 fragmentColor;
                  uniform vec3 u_color;

                  void main()
                  {
                      fragmentColor = u_color;
                  }";
            ShaderProgram sp = Device.CreateShaderProgram(vs, fs);
            ((Uniform<Vector3F>)sp.Uniforms["u_color"]).Value = new Vector3F(1, 0, 0);