I have a project where I have set a shader to draw a circle segment. I'm using a sprite with size of 1x1 pixel for this and scale it to proper size. Everything works fine but the whole thing gets nuts the minute I add a second sprite to the project. After that my shader code is still applied but all the calculations within shader code go crazy. By removing the additional sprite from the project everything goes back to normal. I don't get this problem. There's absolutely no reference to the second sprite anywhere in the object, code or anywhere. EDIT: Exactly same thing seem to happen with GMS2.