abstract class RenderProgram {

 RenderProgram();

 void activate(RenderContextWebGL renderContext);
 void flush();

 //-----------------------------------------------------------------------------------------------

 gl.Shader _createShader(gl.RenderingContext renderingContext, String source, int shaderType) {

   var shader = renderingContext.createShader(shaderType);

   renderingContext.shaderSource(shader, source);
   renderingContext.compileShader(shader);

   var vertexShaderStatus = renderingContext.getShaderParameter(shader, gl.COMPILE_STATUS);
   var isContextLost = renderingContext.isContextLost();
   if (vertexShaderStatus == false && isContextLost == false) {
     throw renderingContext.getShaderInfoLog(shader);
   }

   return shader;
 }

 //-----------------------------------------------------------------------------------------------

 gl.Program createProgram(gl.RenderingContext renderingContext,
                          String vertexShaderSource, String fragmentShaderSource) {

   var program = renderingContext.createProgram();
   var vertexShader = _createShader(renderingContext, vertexShaderSource, gl.VERTEX_SHADER);
   var fragmentShader = _createShader(renderingContext, fragmentShaderSource, gl.FRAGMENT_SHADER);

   renderingContext.attachShader(program, vertexShader);
   renderingContext.attachShader(program, fragmentShader);
   renderingContext.linkProgram(program);

   var programStatus = renderingContext.getProgramParameter(program, gl.LINK_STATUS);
   var isContextLost = renderingContext.isContextLost();
   if (programStatus == false && isContextLost == false) {
     throw renderingContext.getProgramInfoLog(program);
   }

   return program;
 }
}