//////////////////////////////////////////////////////////////////////////////

#ifdef VERTEX

layout (location = 0) in vec2 a_position;
layout (location = 1) in vec2 a_texcoord;

out vec2 v_texcoord;

void main()
{
	v_texcoord = a_texcoord;
	gl_Position = vec4(a_position, 0.0f, 1.0f);
}

#endif

//////////////////////////////////////////////////////////////////////////////

#ifdef FRAGMENT

in vec2 v_texcoord;

out vec4 f_color;

uniform sampler2D u_texture;
uniform float u_powerup_timer;

const float START_TIMER = 15.0f;
const float START_R = 1.20f;
const float START_GB = 0.80f;
const float TIMER_STEPS_R = (START_R-1.0f) / START_TIMER;
const float TIMER_STEPS_GB = (1.0f-START_GB) / START_TIMER;

void main()
{
	vec4 color = texture(u_texture, v_texcoord);

	float gamma = 2.2f;
	if (u_powerup_timer > 0.0f)
	{
		float timer = u_powerup_timer / 100.0f;
		vec3 tint = vec3(
			START_R - (TIMER_STEPS_R*(START_TIMER-u_powerup_timer)),
			START_GB + (TIMER_STEPS_GB*(START_TIMER-u_powerup_timer)),
			START_GB + (TIMER_STEPS_GB*(START_TIMER-u_powerup_timer)));

		color.rgb *= tint;
	}

	f_color = vec4(pow(color.rgb, vec3(1.0f/gamma)), color.a);
}

#endif

//////////////////////////////////////////////////////////////////////////////