shader_type canvas_item;

uniform sampler2D point_texture;
uniform sampler2D trail_texture;

uniform ivec2 point_texture_size;
uniform ivec2 canvas_size;
uniform float point_speed;

varying vec4 data;

// Snippets of code drawn from https://gist.github.com/Bleuje/1e497df4505ca24c39ab3930a95700b3
float gn(in vec2 coordinate, in float seed){
    return fract(tan(distance(coordinate*(seed+0.118446744073709551614), vec2(0.118446744073709551614, 0.314159265358979323846264)))*0.141421356237309504880169);
}

float trail_at_pos(vec2 uv) {
	return texture(trail_texture, uv).r;
}

void vertex() {
	int id = INSTANCE_ID;
	int x = id % point_texture_size.x;
	int y = id / point_texture_size.x;
	// This feels dumb
	vec2 uv = vec2(float(x), float(y));
	vec4 point_data = texture(point_texture, uv);
	
	vec2 pos = point_data.xy;
	float angle = point_data.z;

	//COLOR = vec4(0.2, 0.0, 0.0, 1.0)
	data=vec4(pos, angle, point_data.z);
}

void fragment() {
	COLOR=data;
}