#version 460

#extension GL_GOOGLE_include_directive : require

#include "gui.layout"

layout (location = 0) in vec2 in_dst_start;
layout (location = 1) in vec2 in_dst_end;
layout (location = 2) in vec2 in_src_start;
layout (location = 3) in vec2 in_src_end;
layout (location = 4) in vec4 in_col;

layout (location = 0) out struct FragDataOut {
	vec4 color;
	vec2 uv;
} FragData;

vec2 Vertices[4] = vec2[4](
	vec2(-1.0, +1.0),
	vec2(-1.0, -1.0),
	vec2(+1.0, +1.0),
	vec2(+1.0, -1.0)
);

vec2 rotate(vec2 coords, float theta)
{
	return mat2(cos(theta), sin(theta), -sin(theta), cos(theta)) * coords;
}

void main()
{
	ivec2 tex_size = textureSize(sampler2D(SpriteAtlas, SamplerNearest), 0);

	vec2 dst_half_size = (in_dst_end - in_dst_start) / 2;
	vec2 dst_center = (in_dst_end + in_dst_start) / 2;
	vec2 dst_pos = (Vertices[gl_VertexIndex] * dst_half_size + dst_center);

	vec2 src_half_size = (in_src_end - in_src_start) / 2;
	vec2 src_center = (in_src_end + in_src_start) / 2;
	vec2 src_pos = (Vertices[gl_VertexIndex] * src_half_size + src_center);

	vec2 uvs[4] = vec2[4](
		vec2(in_src_start.x, in_src_start.y),
		vec2(in_src_start.x, in_src_end.y),
		vec2(in_src_end.x, in_src_start.y),
		vec2(in_src_end.x, in_src_end.y)
	);

	FragData.color = in_col;
	FragData.uv = uvs[gl_VertexIndex] / tex_size;

	gl_Position = vec4(2 * dst_pos.x / PC.res.x - 1,
										 2 * dst_pos.y / PC.res.y - 1,
										 0,
										 1);
}