renderdoc/renderdoc/maths/formatpacking.h

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 * The MIT License (MIT)
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 * Copyright (c) 2014 Crytek
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#pragma once

#include <stdint.h>

#include "vec.h"

inline Vec4f ConvertFromR10G10B10A2(uint32_t data)
{
	return Vec4f( float((data>> 0) & 0x3ff) / 1023.0f,
				  float((data>>10) & 0x3ff) / 1023.0f,
				  float((data>>20) & 0x3ff) / 1023.0f,
				  float((data>>30) & 0x003) / 3.0f
				);
}

inline uint32_t ConvertToR10G10B10A2(Vec4f data)
{
	float x = data.x < 1.0f ? (data.x > 0.0f ? data.x : 0.0f) : 1.0f;
	float y = data.y < 1.0f ? (data.y > 0.0f ? data.y : 0.0f) : 1.0f;
	float z = data.z < 1.0f ? (data.z > 0.0f ? data.z : 0.0f) : 1.0f;
	float w = data.w < 1.0f ? (data.w > 0.0f ? data.w : 0.0f) : 1.0f;

	return (uint32_t(x*1023)<< 0) |
		   (uint32_t(y*1023)<<10) |
		   (uint32_t(z*1023)<<20) |
		   (uint32_t(w*3)   <<30) ;
}

inline Vec3f ConvertFromR11G11B10(uint32_t data)
{
	uint32_t mantissas[3] = {
		(data>> 0) & 0x3f,
		(data>>11) & 0x3f,
		(data>>22) & 0x1f,
	};
	int32_t exponents[3] = {
		int32_t(data>> 6) & 0x1f,
		int32_t(data>>17) & 0x1f,
		int32_t(data>>27) & 0x1f,
	};

	Vec3f ret;
	uint32_t *retu = (uint32_t *)&ret.x;

	// floats have 23 bit mantissa, 8bit exponent
	// R11G11B10 has 6/6/5 bit mantissas, 5bit exponents

	const int mantissaShift[] = { 23-6, 23-6, 23-5 };

	for(int i=0; i < 3; i++)
	{
		if(mantissas[i] == 0 && exponents[i] == 0)
		{
			retu[i] = 0;
		}
		else
		{
			if(exponents[i] == 0x1f)
			{
				// infinity or nan
				retu[i] = 0x7f800000 | mantissas[i] << mantissaShift[i];
			}
			else if(exponents[i] != 0)
			{
				// shift exponent and mantissa to the right range for 32bit floats
				retu[i] = (exponents[i] + (127-15)) << 23 | mantissas[i] << mantissaShift[i];
			}
			else if(exponents[i] == 0)
			{
				// we know xMantissa isn't 0 also, or it would have been caught above

				exponents[i] = 1;

				// shift until hidden bit is set
				while((mantissas[i] & 0x40) == 0)
				{
					mantissas[i] <<= 1;
					exponents[i]--;
				}

				// remove the hidden bit
				mantissas[i] &= ~0x40;

				retu[i] = (exponents[i] + (127-15)) << 23 | mantissas[i] << mantissaShift[i];
			}
		}
	}

	return ret;
}

/*
inline uint32_t ConvertToR11G11B10(Vec3f data)
{
	return 0;
}
*/

inline Vec4f ConvertFromB5G5R5A1(uint16_t data)
{
	return Vec4f(  (float)((data >> 0) & 0x1f) / 31.0f,
				   (float)((data >> 5) & 0x1f) / 31.0f,
				   (float)((data >> 10) & 0x1f) / 31.0f,
				   ((data & 0x8000) > 0) ? 1.0f : 0.0f );
}

inline Vec3f ConvertFromB5G6R5(uint16_t data)
{
	return Vec3f( (float)((data >> 0) & 0x1f) / 31.0f,
				  (float)((data >> 5) & 0x3f) / 63.0f,
				  (float)((data >> 11) & 0x1f) / 31.0f );
}

inline Vec4f ConvertFromB4G4R4A4(uint16_t data)
{
	return Vec4f( (float)((data >> 0) & 0xf) / 15.0f,
				  (float)((data >> 4) & 0xf) / 15.0f,
				  (float)((data >> 8) & 0xf) / 15.0f,
				  (float)((data >> 12) & 0xf) / 15.0f );
}

extern float SRGB8_lookuptable[256];

inline float ConvertFromSRGB8(uint8_t comp)
{
	return SRGB8_lookuptable[comp];
}

struct ResourceFormat;
float ConvertComponent(ResourceFormat fmt, byte *data);

#include "half_convert.h"