A brief introduction to batch breaks in GameMaker

gistfile1.txt

"Do you have any resources or info you can throw my way so I can better understand what does and doesn't break a batch?"

1. changing shader and/or setting uniforms
2. changing texture page (handled internally in GM. implicitly changing texture group also causes a batch break, and this too is handled by GM internally)
3. changing surface target
4. some primitives sometimes (though that may have changed now)
5. drawing tilemaps
6. draw_clear()
7. changing blend mode
8. changing matrices
9. vertex_submit (a batch is literally a vertex buffer)
10. rendering out different views
11. probably moving between Draw events? seems likely