Drawing from Vertex Array into Shader

OpenGL OpenGL: Basic Coding
1

Hi all,

i worked a lot with shaders, but only used VBO.
Now i have a APP where i need to draw from Vertex Array.

So here is my render func, i can´t get it working:


void RenderFunction(void)
{
    ++FrameCount;
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    // draw from VBO   <<<<<<<<< worx fine 
    CreateVBO();
    glDrawArrays(GL_LINE_LOOP, 0, 3);


   // draw from Vertex array  <<<<<<< does not draw anything
   GLfloat vVertices[] = {  0.0f,  0.5f, 0.0f, 1.0f,
                           -0.5f, -0.5f, 0.0f, 1.0f,
                            0.5f, -0.5f, 0.0f, 1.0f };

   GLfloat colors[]    = {  0.0f,  0.5f, 0.0f, 1.0f,
                            0.5f,  0.5f, 0.0f, 1.0f,
                            0.5f,  0.5f, 1.0f, 1.0f };

   // Load the vertex data
   glVertexAttribPointer ( 0, 4, GL_FLOAT, GL_FALSE, 0, vVertices );
   glVertexAttribPointer ( 1, 4, GL_FLOAT, GL_FALSE, 0, colors );
   glEnableVertexAttribArray ( 0 );
   glEnableVertexAttribArray ( 1 );

   glDrawArrays ( GL_LINE_LOOP, 0, 3 );

   glDisableVertexAttribArray ( 0 );
   glDisableVertexAttribArray ( 1 );

    glutSwapBuffers();
    glutPostRedisplay();
}

can someone pls tell me where i got my missunderstanding ?
The shader programm is loaded and succesfully used bei the VBO drawing.
Also the attributs in the shader are binded to 0 and 1 - as well used for the VBO.
I also checked the coordinates - they are fine as well.

what do i need to change ?

thanx
uwi

2

If you want to draw using client vertex arrays (which is not supported in the core profile any more), you would need to unbind the VBO before calling glVertexAttribPointer.

3

thanx !!

thjat was it !