/* clang-format off */
[vertex]

layout(location = 0) in highp vec4 vertex_attrib;
/* clang-format on */
layout(location = 4) in vec2 uv_in;

out vec2 uv_interp;

void main() {

	gl_Position = vertex_attrib;
	uv_interp = uv_in;
#ifdef V_FLIP
	uv_interp.y = 1.0 - uv_interp.y;
#endif
}

/* clang-format off */
[fragment]

#if !defined(GLES_OVER_GL)
precision mediump float;
#endif

in vec2 uv_interp;
/* clang-format on */

uniform highp sampler2D source; //texunit:0

uniform float exposure;
uniform float white;

#ifdef USE_AUTO_EXPOSURE

uniform highp sampler2D source_auto_exposure; //texunit:1
uniform highp float auto_exposure_grey;

#endif

#if defined(USE_GLOW_LEVEL1) || defined(USE_GLOW_LEVEL2) || defined(USE_GLOW_LEVEL3) || defined(USE_GLOW_LEVEL4) || defined(USE_GLOW_LEVEL5) || defined(USE_GLOW_LEVEL6) || defined(USE_GLOW_LEVEL7)

uniform highp sampler2D source_glow; //texunit:2
uniform highp float glow_intensity;

#endif

#ifdef USE_BCS

uniform vec3 bcs;

#endif

#ifdef USE_COLOR_CORRECTION

uniform sampler2D color_correction; //texunit:3

#endif

layout(location = 0) out vec4 frag_color;

#ifdef USE_GLOW_FILTER_BICUBIC

// w0, w1, w2, and w3 are the four cubic B-spline basis functions
float w0(float a) {
	return (1.0 / 6.0) * (a * (a * (-a + 3.0) - 3.0) + 1.0);
}

float w1(float a) {
	return (1.0 / 6.0) * (a * a * (3.0 * a - 6.0) + 4.0);
}

float w2(float a) {
	return (1.0 / 6.0) * (a * (a * (-3.0 * a + 3.0) + 3.0) + 1.0);
}

float w3(float a) {
	return (1.0 / 6.0) * (a * a * a);
}

// g0 and g1 are the two amplitude functions
float g0(float a) {
	return w0(a) + w1(a);
}

float g1(float a) {
	return w2(a) + w3(a);
}

// h0 and h1 are the two offset functions
float h0(float a) {
	return -1.0 + w1(a) / (w0(a) + w1(a));
}

float h1(float a) {
	return 1.0 + w3(a) / (w2(a) + w3(a));
}

uniform ivec2 glow_texture_size;

vec4 texture2D_bicubic(sampler2D tex, vec2 uv, int p_lod) {
	float lod = float(p_lod);
	vec2 tex_size = vec2(glow_texture_size >> p_lod);
	vec2 pixel_size = 1.0 / tex_size;
	uv = uv * tex_size + 0.5;
	vec2 iuv = floor(uv);
	vec2 fuv = fract(uv);

	float g0x = g0(fuv.x);
	float g1x = g1(fuv.x);
	float h0x = h0(fuv.x);
	float h1x = h1(fuv.x);
	float h0y = h0(fuv.y);
	float h1y = h1(fuv.y);

	vec2 p0 = (vec2(iuv.x + h0x, iuv.y + h0y) - 0.5) * pixel_size;
	vec2 p1 = (vec2(iuv.x + h1x, iuv.y + h0y) - 0.5) * pixel_size;
	vec2 p2 = (vec2(iuv.x + h0x, iuv.y + h1y) - 0.5) * pixel_size;
	vec2 p3 = (vec2(iuv.x + h1x, iuv.y + h1y) - 0.5) * pixel_size;

	return (g0(fuv.y) * (g0x * textureLod(tex, p0, lod) + g1x * textureLod(tex, p1, lod))) +
		   (g1(fuv.y) * (g0x * textureLod(tex, p2, lod) + g1x * textureLod(tex, p3, lod)));
}

#define GLOW_TEXTURE_SAMPLE(m_tex, m_uv, m_lod) texture2D_bicubic(m_tex, m_uv, m_lod)

#else

#define GLOW_TEXTURE_SAMPLE(m_tex, m_uv, m_lod) textureLod(m_tex, m_uv, float(m_lod))

#endif

vec3 tonemap_filmic(vec3 color, float white) {

	float A = 0.15;
	float B = 0.50;
	float C = 0.10;
	float D = 0.20;
	float E = 0.02;
	float F = 0.30;
	float W = 11.2;

	vec3 coltn = ((color * (A * color + C * B) + D * E) / (color * (A * color + B) + D * F)) - E / F;
	float whitetn = ((white * (A * white + C * B) + D * E) / (white * (A * white + B) + D * F)) - E / F;

	return coltn / whitetn;
}

vec3 tonemap_aces(vec3 color) {
	float a = 2.51f;
	float b = 0.03f;
	float c = 2.43f;
	float d = 0.59f;
	float e = 0.14f;
	return color = clamp((color * (a * color + b)) / (color * (c * color + d) + e), vec3(0.0), vec3(1.0));
}

vec3 tonemap_reindhart(vec3 color, float white) {

	return (color * (1.0 + (color / (white)))) / (1.0 + color);
}

void main() {

	vec4 color = textureLod(source, uv_interp, 0.0);

#ifdef USE_AUTO_EXPOSURE

	color /= texelFetch(source_auto_exposure, ivec2(0, 0), 0).r / auto_exposure_grey;
#endif

	color *= exposure;

#if defined(USE_GLOW_LEVEL1) || defined(USE_GLOW_LEVEL2) || defined(USE_GLOW_LEVEL3) || defined(USE_GLOW_LEVEL4) || defined(USE_GLOW_LEVEL5) || defined(USE_GLOW_LEVEL6) || defined(USE_GLOW_LEVEL7)
#define USING_GLOW
#endif

#if defined(USING_GLOW)
	vec3 glow = vec3(0.0);

#ifdef USE_GLOW_LEVEL1

	glow += GLOW_TEXTURE_SAMPLE(source_glow, uv_interp, 1).rgb;
#endif

#ifdef USE_GLOW_LEVEL2
	glow += GLOW_TEXTURE_SAMPLE(source_glow, uv_interp, 2).rgb;
#endif

#ifdef USE_GLOW_LEVEL3
	glow += GLOW_TEXTURE_SAMPLE(source_glow, uv_interp, 3).rgb;
#endif

#ifdef USE_GLOW_LEVEL4
	glow += GLOW_TEXTURE_SAMPLE(source_glow, uv_interp, 4).rgb;
#endif

#ifdef USE_GLOW_LEVEL5
	glow += GLOW_TEXTURE_SAMPLE(source_glow, uv_interp, 5).rgb;
#endif

#ifdef USE_GLOW_LEVEL6
	glow += GLOW_TEXTURE_SAMPLE(source_glow, uv_interp, 6).rgb;
#endif

#ifdef USE_GLOW_LEVEL7
	glow += GLOW_TEXTURE_SAMPLE(source_glow, uv_interp, 7).rgb;
#endif

	glow *= glow_intensity;

#endif

#ifdef USE_REINDHART_TONEMAPPER

	color.rgb = tonemap_reindhart(color.rgb, white);

#if defined(USING_GLOW)
	glow = tonemap_reindhart(glow, white);
#endif

#endif

#ifdef USE_FILMIC_TONEMAPPER

	color.rgb = tonemap_filmic(color.rgb, white);

#if defined(USING_GLOW)
	glow = tonemap_filmic(glow, white);
#endif

#endif

#ifdef USE_ACES_TONEMAPPER

	color.rgb = tonemap_aces(color.rgb);

#if defined(USING_GLOW)
	glow = tonemap_aces(glow);
#endif

#endif

	//regular Linear -> SRGB conversion
	vec3 a = vec3(0.055);
	color.rgb = mix((vec3(1.0) + a) * pow(color.rgb, vec3(1.0 / 2.4)) - a, 12.92 * color.rgb, lessThan(color.rgb, vec3(0.0031308)));

#if defined(USING_GLOW)
	glow = mix((vec3(1.0) + a) * pow(glow, vec3(1.0 / 2.4)) - a, 12.92 * glow, lessThan(glow, vec3(0.0031308)));
#endif

	//glow needs to be added in SRGB space (together with image space effects)

	color.rgb = clamp(color.rgb, 0.0, 1.0);

#if defined(USING_GLOW)
	glow = clamp(glow, 0.0, 1.0);
#endif

#ifdef USE_GLOW_REPLACE

	color.rgb = glow;

#endif

#ifdef USE_GLOW_SCREEN

	color.rgb = max((color.rgb + glow) - (color.rgb * glow), vec3(0.0));

#endif

#ifdef USE_GLOW_SOFTLIGHT

	{

		glow = (glow * 0.5) + 0.5;
		color.r = (glow.r <= 0.5) ? (color.r - (1.0 - 2.0 * glow.r) * color.r * (1.0 - color.r)) : (((glow.r > 0.5) && (color.r <= 0.25)) ? (color.r + (2.0 * glow.r - 1.0) * (4.0 * color.r * (4.0 * color.r + 1.0) * (color.r - 1.0) + 7.0 * color.r)) : (color.r + (2.0 * glow.r - 1.0) * (sqrt(color.r) - color.r)));
		color.g = (glow.g <= 0.5) ? (color.g - (1.0 - 2.0 * glow.g) * color.g * (1.0 - color.g)) : (((glow.g > 0.5) && (color.g <= 0.25)) ? (color.g + (2.0 * glow.g - 1.0) * (4.0 * color.g * (4.0 * color.g + 1.0) * (color.g - 1.0) + 7.0 * color.g)) : (color.g + (2.0 * glow.g - 1.0) * (sqrt(color.g) - color.g)));
		color.b = (glow.b <= 0.5) ? (color.b - (1.0 - 2.0 * glow.b) * color.b * (1.0 - color.b)) : (((glow.b > 0.5) && (color.b <= 0.25)) ? (color.b + (2.0 * glow.b - 1.0) * (4.0 * color.b * (4.0 * color.b + 1.0) * (color.b - 1.0) + 7.0 * color.b)) : (color.b + (2.0 * glow.b - 1.0) * (sqrt(color.b) - color.b)));
	}

#endif

#if defined(USING_GLOW) && !defined(USE_GLOW_SCREEN) && !defined(USE_GLOW_SOFTLIGHT) && !defined(USE_GLOW_REPLACE)
	//additive
	color.rgb += glow;
#endif

#ifdef USE_BCS

	color.rgb = mix(vec3(0.0), color.rgb, bcs.x);
	color.rgb = mix(vec3(0.5), color.rgb, bcs.y);
	color.rgb = mix(vec3(dot(vec3(1.0), color.rgb) * 0.33333), color.rgb, bcs.z);

#endif

#ifdef USE_COLOR_CORRECTION

	color.r = texture(color_correction, vec2(color.r, 0.0)).r;
	color.g = texture(color_correction, vec2(color.g, 0.0)).g;
	color.b = texture(color_correction, vec2(color.b, 0.0)).b;
#endif

	frag_color = vec4(color.rgb, 1.0);
}