shader_type canvas_item;

// Photoshop-style corner offsets in pixels
uniform vec2 top_left = vec2(0.0);
uniform vec2 top_right = vec2(0.0);
uniform vec2 bottom_left = vec2(0.0);
uniform vec2 bottom_right = vec2(0.0);

void vertex() {
	// 1. Calculate UV based on the vertex position relative to size
	vec2 size = 1.0 / TEXTURE_PIXEL_SIZE;
	vec2 uv = VERTEX / size;
	
	// 2. Linear interpolation to find the offset for this specific vertex
	// This maps the square to whatever quadrilateral you define
	vec2 top_row = mix(top_left, top_right, uv.x);
	vec2 bottom_row = mix(bottom_left, bottom_right, uv.x);
	vec2 final_offset = mix(top_row, bottom_row, uv.y);
	
	VERTEX += final_offset;
}