qzdoom/src/r_data/colormaps.h

#ifndef __RES_CMAP_H
#define __RES_CMAP_H

#include "m_fixed.h"

struct FSWColormap;
struct lightlist_t;

void R_InitColormaps ();
void R_DeinitColormaps ();

uint32_t R_ColormapNumForName(const char *name);	// killough 4/4/98
void R_SetDefaultColormap (const char *name);	// [RH] change normal fadetable
uint32_t R_BlendForColormap (uint32_t map);			// [RH] return calculated blend for a colormap
extern FSWColormap realcolormaps;					// [RH] make the colormaps externally visible
extern size_t numfakecmaps;

// for internal use
struct FColormap
{
	PalEntry		LightColor;		// a is saturation (0 full, 31=b/w, other=custom colormap)
	PalEntry		FadeColor;		// a is fadedensity>>1
	uint8_t			Desaturation;
	uint8_t			BlendFactor;	// This is for handling Legacy-style colormaps which use a different formula to calculate how the color affects lighting.
	uint16_t		FogDensity;

	void Clear()
	{
		LightColor = 0xffffff;
		FadeColor = 0;
		Desaturation = 0;
		BlendFactor = 0;
		FogDensity = 0;
	}

	void MakeWhite()
	{
		LightColor = 0xffffff;
	}

	void ClearColor()
	{
		LightColor = 0xffffff;
		BlendFactor = 0;
		Desaturation = 0;
	}

	void CopyLight(FColormap &from)
	{
		LightColor = from.LightColor;
		Desaturation = from.Desaturation;
		BlendFactor = from.BlendFactor;
	}

	void CopyFog(FColormap &from)
	{
		FadeColor = from.FadeColor;
		FogDensity = from.FogDensity;
	}

	void CopyFrom3DLight(lightlist_t *light);

	void Decolorize()	// this for 'nocoloredspritelighting' and not the same as desaturation. The normal formula results in a value that's too dark.
	{
		int v = (LightColor.r + LightColor.g + LightColor.b) / 3;
		LightColor.r = LightColor.g = LightColor.b = (255 + v + v) / 3;
	}

	bool operator == (const FColormap &other)
	{
		return LightColor == other.LightColor && FadeColor == other.FadeColor && Desaturation == other.Desaturation &&
			BlendFactor == other.BlendFactor && FogDensity == other.FogDensity;
	}

	bool operator != (const FColormap &other)
	{
		return !operator==(other);
	}

};

struct FSWColormap
{
	uint8_t *Maps = nullptr;
	PalEntry Color = 0xffffffff;
	PalEntry Fade = 0xff000000;
	int Desaturate = 0;
};

struct FDynamicColormap : FSWColormap
{
	void ChangeFade (PalEntry fadecolor);
	void ChangeColor (PalEntry lightcolor, int desaturate);
	void ChangeColorFade (PalEntry lightcolor, PalEntry fadecolor);
	void ChangeFogDensity(int newdensity);
	void BuildLights ();
	static void RebuildAllLights();

	FDynamicColormap *Next;
};


// For hardware-accelerated weapon sprites in colored sectors
struct FColormapStyle
{
	PalEntry Color;
	PalEntry Fade;
	int Desaturate;
	float FadeLevel;
};

enum
{
	NOFIXEDCOLORMAP = -1,
	INVERSECOLORMAP,	// the inverse map is used explicitly in a few places.
};


struct FSpecialColormap : FSWColormap
{
	FSpecialColormap()
	{
		Maps = Colormap;
	}

	float ColorizeStart[3];
	float ColorizeEnd[3];
	uint8_t Colormap[256];
	PalEntry GrayscaleToColor[256];
};

extern TArray<FSpecialColormap> SpecialColormaps;

// some utility functions to store special colormaps in powerup blends
#define SPECIALCOLORMAP_MASK 0x00b60000

inline uint32_t MakeSpecialColormap(int index)
{
	assert(index >= 0 && index < 65536);
	return index | SPECIALCOLORMAP_MASK;
}

int AddSpecialColormap(float r1, float g1, float b1, float r2, float g2, float b2);



extern uint8_t DesaturateColormap[31][256];
extern FDynamicColormap NormalLight;
extern FDynamicColormap FullNormalLight;
extern bool NormalLightHasFixedLights;

FDynamicColormap *GetSpecialLights (PalEntry lightcolor, PalEntry fadecolor, int desaturate);

__forceinline FDynamicColormap *GetColorTable(const FColormap &cm)
{
	auto p = &NormalLight;
	if (cm.LightColor == p->Color &&
		cm.FadeColor == p->Fade &&
		cm.Desaturation == p->Desaturate)
	{
		return p;
	}

	return GetSpecialLights(cm.LightColor, cm.FadeColor, cm.Desaturation);
}

#endif