Render 2 images that uses different shaders
- by Code Vader
Based on the giawa/nehe tutorials, how can I render 2 images with different shaders. I'm pretty new to OpenGl and shaders so I'm not completely sure whats happening in my code, but I think the shaders that is called last overwrites the first one.
private static void OnRenderFrame()
{
// calculate how much time has elapsed since the last frame
watch.Stop();
float deltaTime = (float)watch.ElapsedTicks / System.Diagnostics.Stopwatch.Frequency;
watch.Restart();
// use the deltaTime to adjust the angle of the cube
angle += deltaTime;
// set up the OpenGL viewport and clear both the color and depth bits
Gl.Viewport(0, 0, width, height);
Gl.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);
// use our shader program and bind the crate texture
Gl.UseProgram(program);
//<<<<<<<<<<<< TOP PYRAMID
// set the transformation of the top_pyramid
program["model_matrix"].SetValue(Matrix4.CreateRotationY(angle * rotate_cube));
program["enable_lighting"].SetValue(lighting);
// bind the vertex positions, UV coordinates and element array
Gl.BindBufferToShaderAttribute(top_pyramid, program, "vertexPosition");
Gl.BindBufferToShaderAttribute(top_pyramidNormals, program, "vertexNormal");
Gl.BindBufferToShaderAttribute(top_pyramidUV, program, "vertexUV");
Gl.BindBuffer(top_pyramidTrianlges);
// draw the textured top_pyramid
Gl.DrawElements(BeginMode.Triangles, top_pyramidTrianlges.Count, DrawElementsType.UnsignedInt, IntPtr.Zero);
//<<<<<<<<<< CUBE
// set the transformation of the cube
program["model_matrix"].SetValue(Matrix4.CreateRotationY(angle * rotate_cube));
program["enable_lighting"].SetValue(lighting);
// bind the vertex positions, UV coordinates and element array
Gl.BindBufferToShaderAttribute(cube, program, "vertexPosition");
Gl.BindBufferToShaderAttribute(cubeNormals, program, "vertexNormal");
Gl.BindBufferToShaderAttribute(cubeUV, program, "vertexUV");
Gl.BindBuffer(cubeQuads);
// draw the textured cube
Gl.DrawElements(BeginMode.Quads, cubeQuads.Count, DrawElementsType.UnsignedInt, IntPtr.Zero);
//<<<<<<<<<<<< BOTTOM PYRAMID
// set the transformation of the bottom_pyramid
program["model_matrix"].SetValue(Matrix4.CreateRotationY(angle * rotate_cube));
program["enable_lighting"].SetValue(lighting);
// bind the vertex positions, UV coordinates and element array
Gl.BindBufferToShaderAttribute(bottom_pyramid, program, "vertexPosition");
Gl.BindBufferToShaderAttribute(bottom_pyramidNormals, program, "vertexNormal");
Gl.BindBufferToShaderAttribute(bottom_pyramidUV, program, "vertexUV");
Gl.BindBuffer(bottom_pyramidTrianlges);
// draw the textured bottom_pyramid
Gl.DrawElements(BeginMode.Triangles, bottom_pyramidTrianlges.Count, DrawElementsType.UnsignedInt, IntPtr.Zero);
//<<<<<<<<<<<<< STAR
Gl.Disable(EnableCap.DepthTest);
Gl.Enable(EnableCap.Blend);
Gl.BlendFunc(BlendingFactorSrc.SrcAlpha, BlendingFactorDest.One);
Gl.BindTexture(starTexture);
//calculate the camera position using some fancy polar co-ordinates
Vector3 position = 20 * new Vector3(Math.Cos(phi) * Math.Sin(theta), Math.Cos(theta), Math.Sin(phi) * Math.Sin(theta));
Vector3 upVector = ((theta % (Math.PI * 2)) > Math.PI) ? Vector3.Up : Vector3.Down;
program_2["view_matrix"].SetValue(Matrix4.LookAt(position, Vector3.Zero, upVector));
// make sure the shader program and texture are being used
Gl.UseProgram(program_2);
// loop through the stars, drawing each one
for (int i = 0; i < stars.Count; i++)
{
// set the position and color of this star
program_2["model_matrix"].SetValue(Matrix4.CreateTranslation(new Vector3(stars[i].dist, 0, 0)) * Matrix4.CreateRotationZ(stars[i].angle));
program_2["color"].SetValue(stars[i].color);
Gl.BindBufferToShaderAttribute(star, program_2, "vertexPosition");
Gl.BindBufferToShaderAttribute(starUV, program_2, "vertexUV");
Gl.BindBuffer(starQuads);
Gl.DrawElements(BeginMode.Quads, starQuads.Count, DrawElementsType.UnsignedInt, IntPtr.Zero);
// update the position of the star
stars[i].angle += (float)i / stars.Count * deltaTime * 2 * rotate_stars;
stars[i].dist -= 0.2f * deltaTime * rotate_stars;
// if we've reached the center then move this star outwards and give it a new color
if (stars[i].dist < 0f)
{
stars[i].dist += 5f;
stars[i].color = new Vector3(generator.NextDouble(), generator.NextDouble(), generator.NextDouble());
}
}
Glut.glutSwapBuffers();
}
The same goes for the textures, whichever one I mention last gets applied to both object?
