Using Texture and vertex (with texture mapping) in OPENGL renderer

Processing Coding Questions
1

Hello all,

I’ve been googling and searching the forum, but can’t seem to find how to make this work. This may have to do with my total absence of OPENGL-knowledge.

I am drawing shapes with vertices, and apply an image as a texture on them:

textureMode(NORMAL);
beginShape();
if(use_heatmap){
  tint(255, getTrans());
}
texture(texture);
vertex(x, y, 0, 0);
vertex(x+w, y, 1, 0);
vertex(x+w, y+h, 1, 1);
vertex(x, y+h, 0, 1);
endShape();

This works, but I only got this to work when using P2D as the renderer.
Now I have to switch to the default renderer again because I want to use something like:

heatmap_graphics.beginDraw();
heatmap_graphics.image(heatmap_movie, 0, 0, width, height);
heatmap_graphics.endDraw();

And use this PGraphics as input somewhere else in the code.

So I have the problem that one piece of code is working with one renderer, the other with the default renderer.

My question: If I want to use the default renderer, how can I change the code of the vertices with UV-mapping a picture? Everything I google about OPENGL is like abracadabra to me and I get lost.

Thanks for your time and input!