#version 330

//s_texture points to an indexed color texture
uniform sampler2D s_texture;
//s_palswap is the palette swap texture where u is the color index and v is the shade
uniform sampler2D s_palswap;
//s_palette is the base palette texture where u is the color index
uniform sampler2D s_palette;

uniform sampler2D s_detail;
uniform sampler2D s_glow;

uniform vec2 u_palswapPos;
uniform vec2 u_palswapSize;

uniform vec2 u_clamp;

uniform float u_shade;
uniform float u_numShades;
uniform float u_visFactor;
uniform float u_fogEnabled;

uniform float u_useColorOnly;
uniform float u_usePalette;
uniform float u_npotEmulation;
uniform float u_npotEmulationFactor;
uniform float u_npotEmulationXOffset;
uniform float u_shadeInterpolate;
uniform float u_brightness;
uniform vec4 u_fog;
uniform vec4 u_fogColor;

uniform float u_useDetailMapping;
uniform float u_useGlowMapping;

uniform int u_tinteffect;
uniform vec3 u_tintcolor;

in vec4 v_color;
in float v_distance;
in vec4 v_texCoord;
in vec4 v_detailCoord;
in vec4 v_glowCoord;
in float v_fogCoord;

const float c_basepalScale = 255.0/256.0;
const float c_basepalOffset = 0.5/256.0;

const float c_zero = 0.0;
const float c_one = 1.0;
const float c_two = 2.0;
const vec4 c_vec4_one = vec4(c_one);
const float c_wrapThreshold = 0.9;

layout(location=0) out vec4 fragColor;

layout(std140) uniform Palette {
	vec4 palette[256];
};

layout(std140) uniform Palswap {
	int palswap[256];
};

//===========================================================================
//
// Color to grayscale
//
//===========================================================================

float grayscale(vec4 color)
{
	return dot(color.rgb, vec3(0.3, 0.56, 0.14));
}
 
//===========================================================================
//
// Hightile tinting code. (hictinting[dapalnum]) This can be done inside the shader 
// to avoid costly texture duplication (but needs a more modern GLSL than 1.10.)
//
//===========================================================================

vec4 convertColor(vec4 color, int effect, vec3 tint)
{
#if 0

	if (effect & HICTINT_GRAYSCALE)
	{
		float g = grayscale(color);
		color = vec4(g, g, g, color.a);
	}

	if (effect & HICTINT_INVERT)
	{
		color = vec4(1.0 - color.r, 1.0 - color.g, 1.0 - color.b);
	}
	
	vec3 tcol = color.rgb * 255.0;	// * 255.0 to make it easier to reuse the integer math.
	tint *= 255.0;

	if (effect & HICTINT_COLORIZE)
	{
		tcol.b = min(((tcol.b) * tint.r) / 64.0, 255.0);
		tcol.g = min(((tcol.g) * tint.g) / 64.0, 255.0);
		tcol.r = min(((tcol.r) * tint.b) / 64.0, 255.0);
	}

	switch (effect & HICTINT_BLENDMASK)
	{
		case HICTINT_BLEND_SCREEN:
			tcol.b = 255.0 - (((255.0 - tcol.b) * (255.0 - tint.r)) / 256.0);
			tcol.g = 255.0 - (((255.0 - tcol.g) * (255.0 - tint.g)) / 256.0);
			tcol.r = 255.0 - (((255.0 - tcol.r) * (255.0 - tint.b)) / 256.0);
			break;
		case HICTINT_BLEND_OVERLAY:
			tcol.b = tcol.b < 128.0? (tcol.b * tint.r) / 128.0 : 255.0 - (((255.0 - tcol.b) * (255.0 - tint.r)) / 128.0);
			tcol.g = tcol.g < 128.0? (tcol.g * tint.g) / 128.0 : 255.0 - (((255.0 - tcol.g) * (255.0 - tint.g)) / 128.0);
			tcol.r = tcol.r < 128.0? (tcol.r * tint.b) / 128.0 : 255.0 - (((255.0 - tcol.r) * (255.0 - tint.b)) / 128.0);
			break;
		case HICTINT_BLEND_HARDLIGHT:
			tcol.b = tint.r < 128.0 ? (tcol.b * tint.r) / 128.0 : 255.0 - (((255.0 - tcol.b) * (255.0 - r)) / 128.0);
			tcol.g = tint.g < 128.0 ? (tcol.g * tint.g) / 128.0 : 255.0 - (((255.0 - tcol.g) * (255.0 - g)) / 128.0);
			tcol.r = tint.b < 128.0 ? (tcol.r * tint.b) / 128.0 : 255.0 - (((255.0 - tcol.r) * (255.0 - b)) / 128.0);
			break;
	}
	color.rgb = tcol / 255.0;
#endif
	return color;
}

//===========================================================================
//
// Talk about all the wrong way of being 'efficient'... :(
//
//===========================================================================

void main()
{
	float coordX = v_texCoord.x;
	float coordY = v_texCoord.y;
	vec2 newCoord;
		
	// Coordinate adjustment for NPOT textures (something must have gone very wrong to make this necessary...)
	if (u_npotEmulation != 0.0)
	{
		float period = floor(coordY / u_npotEmulationFactor);
		coordX += u_npotEmulationXOffset * floor(mod(coordY, u_npotEmulationFactor));
		coordY = period + mod(coordY, u_npotEmulationFactor);
	}
	newCoord = vec2(coordX, coordY);
#if 1
	if (u_clamp != 0.0) newCoord = clamp(newCoord.xy, 0.0, 1.0);
#else	
	// what is this for? The only effect I could observe was a significant degradation of anisotropic filtering.
	vec2 transitionBlend = fwidth(floor(newCoord.xy));
	transitionBlend = fwidth(transitionBlend) + transitionBlend;
		
	vec2 val1 = mix(fract(newCoord.xy), abs(1.0-mod(newCoord.xy+1.0, 2.0)), transitionBlend);
	vec2 clampedCoord = clamp(newCoord.xy, 0.0, 1.0);
	newCoord = mix(val1, clampedCoord, u_clamp);
#endif
	vec4 color = texture2D(s_texture, newCoord);

    float shade = clamp((u_shade+max(u_visFactor*v_distance-0.5*u_shadeInterpolate,c_zero)), c_zero, u_numShades-c_one);
    float shadeFrac = mod(shade, c_one);
    float colorIndex = texture2D(s_palswap, u_palswapPos+u_palswapSize*vec2(color.r, floor(shade)/u_numShades)).r;
    colorIndex = c_basepalOffset + c_basepalScale*colorIndex;
    vec4 palettedColor = texture2D(s_palette, vec2(colorIndex, c_zero));
    colorIndex = texture2D(s_palswap, u_palswapPos+u_palswapSize*vec2(color.r, (floor(shade)+c_one)/u_numShades)).r;
    colorIndex = c_basepalOffset + c_basepalScale*colorIndex;
    vec4 palettedColorNext = texture2D(s_palette, vec2(colorIndex, c_zero));
    palettedColor.rgb = mix(palettedColor.rgb, palettedColorNext.rgb, shadeFrac*u_shadeInterpolate);
    float fullbright = mix(u_usePalette*palettedColor.a, c_zero, u_useColorOnly);	// This only gets set for paletted rendering.
    palettedColor.a = c_one-floor(color.r);
    color = mix(color, palettedColor, u_usePalette);

	if (u_useDetailMapping != 0.0)
	{
		vec4 detailColor = texture2D(s_detail, v_detailCoord.xy);
		detailColor = mix(c_vec4_one, 2.0*detailColor, detailColor.a);
		color.rgb *= detailColor.rgb;
	}

	// should be an 'else' to all the above.
	color = mix(color, c_vec4_one, u_useColorOnly);

	// only relevant for paletted rendering - in true color this requires a fifth color channel (i.e. an external brightmap - work for later) or an overlay (current implementation)
    	color.rgb = mix(v_color.rgb*color.rgb, color.rgb, fullbright);

	if (u_usePalette == 0.0 && u_fogEnabled != 0.0)// the following would make sense if 'fullbright' could ever be true in non-paletted rendering: && (fullbright != 0.0 || u_fogColor.rgb != vec3(0.0) ))
	{
		float fogFactor;

		if (u_fog.z == 0) fogFactor = (u_fog.x-v_fogCoord)*u_fog.y;	// linear fog
 		else fogFactor = exp2 (u_fog.z * v_fogCoord); 				// exponential fog

		fogFactor = clamp(fogFactor, 0.0, 1.0);
		color.rgb = mix(u_fogColor.rgb, color.rgb, fogFactor);
	}

	if (u_useGlowMapping != 0.0 && u_useColorOnly == 0.0)
	{
		vec4 glowColor = texture2D(s_glow, v_glowCoord.xy);
		color.rgb = mix(color.rgb, glowColor.rgb, glowColor.a);
	}
	
	color.a *= v_color.a;
	color.rgb = pow(color.rgb, vec3(u_brightness));
	fragColor = color;
}