title: Drawing part of a texture on a triangle in openGL
body: <p>I'm trying to draw part of a texture on a triangle. The triangle is defined by 3 points. One of the points will always be the center of the image. Now I want to draw a part of the texture on that triangle. So the triangle would cut out that part of the image and draw it on itself. But I don't want the texture to scale when drawn. It has to stay the same. So even if the triangle's base points fall outside of the image. The image can't be scaled. I don't understand how this can be done. Whenever I play around with texturing, the image gets scaled or drawn multiple times it seems.</p>
  
  <p>Here is an image: so the red triangle would be drawn exactly like that in openGL. </p>
  
  <p><img src="https://i.stack.imgur.com/akOFT.png" alt="enter image description here"></p>