Cutting part of texture

Question

Hey guys I'm writing for iPhone, OpenGL ES

Do you know how can I draw quad with part of particular texture?

Now I'm rendering like that:

 static const GLfloat texCoords[] = {
   0.0, 0.0,
   10.0, 0.0,
   10.0, 10.0,
   0.0, 10.0
  };
 glBindTexture(GL_TEXTURE_2D, atlas_tex[0]);

  GLfloat squareVertices[] = {
   0.0f, 0.0f,
   2000.5f, 0.0f,
   2000.5f,  2000.33f,
   0.0f,  2000.33f
  };


    glVertexPointer(2, GL_FLOAT, 0, squareVertices);
    glEnableClientState(GL_VERTEX_ARRAY);
 glTexCoordPointer(2, GL_FLOAT, 0, texCoords);
 glEnableClientState(GL_TEXTURE_COORD_ARRAY);

    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

But of course, it display all texture. I don't know how to cut it.

Answer 1

If I understood you correctly, you need to change the texCoords array appropriately.

E.g. try something like that:

static const GLfloat texCoords[] = {
  0.0, 0.0,
  0.5, 0.0,
  0.5, 0.5,
  0.0, 0.5
};