# version 450

layout(location = 0) in vec4 in_fg_color;
layout(location = 1) in vec4 in_bg_color;
layout(location = 2) in vec4 in_sprite_region;
layout(location = 3) in vec2 in_uv;
layout(location = 4) in float in_width;

layout(location = 0) out vec4 out_color;

layout(binding = 1) uniform sampler2D mtsdfSampler;

float median(float r, float g, float b) {
	return max(min(r, g), min(max(r, g), b));
}

void main() {
	vec2 atlas_coord = (in_uv - in_sprite_region.xy) / in_sprite_region.zw;
	vec4 msd = texture(mtsdfSampler, atlas_coord);
	float sd = median(msd.r, msd.g, msd.b);
	float screenPxDistance = in_width * (sd - 0.5);
	float opacity = clamp(screenPxDistance + 0.5, 0.0, 1.0);
	out_color = mix(in_bg_color, in_fg_color, opacity);
}