#version 430 core

in Fragment
{
	// @Performance: Are this fields aligned to vec4? Is it better to reorder them?
	vec2 position;
	vec4 color;
	vec2 uv;
} frag;

uniform int width;  // Width  of the screen in pixels
uniform int height; // Height of the screen in pixels

uniform int has_texture0;
uniform sampler2D texture0;
uniform int texture_channels0;
uniform vec4 color0;

out vec4 FragColor;

void main()
{
	FragColor = frag.color;

	if(has_texture0 != 0)
	{
		vec4 texture_color;
		if(texture_channels0 == 1)
			texture_color = vec4(1.0, 1.0, 1.0, texture(texture0, frag.uv).r);
		else if(texture_channels0 == 3)
			texture_color = vec4(texture(texture0, frag.uv).rgb, 1.0);
		else
			texture_color = texture(texture0, frag.uv);

		FragColor = color0 * frag.color * texture_color;
		FragColor.rgb *= FragColor.a; // Premultiplied alpha
	}
}