nvidia-texture-tools/src/nvmath/Color.h

// This code is in the public domain -- castanyo@yahoo.es

#pragma once
#ifndef NV_MATH_COLOR_H
#define NV_MATH_COLOR_H

#include "nvcore/Debug.h"
#include "nvmath/Vector.h"

namespace nv
{

    /// 64 bit color stored as BGRA.
    class NVMATH_CLASS Color64 
    {
    public:
        Color64() { }
        Color64(const Color64 & c) : u(c.u) { }
        Color64(uint16 R, uint16 G, uint16 B, uint16 A) { setRGBA(R, G, B, A); }
        explicit Color64(uint64 U) : u(U) { }

        void setRGBA(uint16 R, uint16 G, uint16 B, uint16 A)
        {
            r = R;
            g = G;
            b = B;
            a = A;
        }

        operator uint64 () const {
            return u;
        }

        union {
            struct {
#if NV_LITTLE_ENDIAN
                uint16 r, a, b, g;
#else
                uint16 a: 16;
                uint16 r: 16;
                uint16 g: 16;
                uint16 b: 16;
#endif
            };
            uint64 u;
        };
    };

    /// 32 bit color stored as BGRA.
    class NVMATH_CLASS Color32
    {
    public:
        Color32() { }
        Color32(const Color32 & c) : u(c.u) { }
        Color32(uint8 R, uint8 G, uint8 B) { setRGBA(R, G, B, 0xFF); }
        Color32(uint8 R, uint8 G, uint8 B, uint8 A) { setRGBA( R, G, B, A); }
        //Color32(uint8 c[4]) { setRGBA(c[0], c[1], c[2], c[3]); }
        //Color32(float R, float G, float B) { setRGBA(uint(R*255), uint(G*255), uint(B*255), 0xFF); }
        //Color32(float R, float G, float B, float A) { setRGBA(uint(R*255), uint(G*255), uint(B*255), uint(A*255)); }
        explicit Color32(uint32 U) : u(U) { }

        void setRGBA(uint8 R, uint8 G, uint8 B, uint8 A)
        {
            r = R;
            g = G;
            b = B;
            a = A;
        }

        void setBGRA(uint8 B, uint8 G, uint8 R, uint8 A = 0xFF)
        {
            r = R;
            g = G;
            b = B;
            a = A;
        }

        operator uint32 () const {
            return u;
        }

        union {
            struct {
#if NV_LITTLE_ENDIAN
                uint8 b, g, r, a;
#else
                uint8 a: 8;
                uint8 r: 8;
                uint8 g: 8;
                uint8 b: 8;
#endif
            };
            uint32 u;
        };
    };


    /// 16 bit 565 BGR color.
    class NVMATH_CLASS Color16
    {
    public:
        Color16() { }
        Color16(const Color16 & c) : u(c.u) { }
        explicit Color16(uint16 U) : u(U) { }

        union {
            struct {
#if NV_LITTLE_ENDIAN
                uint16 b : 5;
                uint16 g : 6;
                uint16 r : 5;
#else
                uint16 r : 5;
                uint16 g : 6;
                uint16 b : 5;
#endif
            };
            uint16 u;
        };
    };


    /// Clamp color components.
    inline Vector3 colorClamp(Vector3::Arg c)
    {
        return Vector3(clamp(c.x, 0.0f, 1.0f), clamp(c.y, 0.0f, 1.0f), clamp(c.z, 0.0f, 1.0f));
    }

    /// Clamp without allowing the hue to change.
    inline Vector3 colorNormalize(Vector3::Arg c)
    {
        float scale = 1.0f;
        if (c.x > scale) scale = c.x;
        if (c.y > scale) scale = c.y;
        if (c.z > scale) scale = c.z;
        return c / scale;
    }

    /// Convert Color32 to Color16.
    inline Color16 toColor16(Color32 c)
    {
        Color16 color;
        //         rrrrrggggggbbbbb
        // rrrrr000gggggg00bbbbb000
        //	color.u = (c.u >> 3) & 0x1F;
        //	color.u |= (c.u >> 5) & 0x7E0;
        //	color.u |= (c.u >> 8) & 0xF800;

        color.r = c.r >> 3;
        color.g = c.g >> 2;
        color.b = c.b >> 3;
        return color; 
    }


    /// Promote 16 bit color to 32 bit using regular bit expansion.
    inline Color32 toColor32(Color16 c)
    {
        Color32 color;
        //	c.u = ((col0.u << 3) & 0xf8) | ((col0.u << 5) & 0xfc00) | ((col0.u << 8) & 0xf80000);
        //	c.u |= (c.u >> 5) & 0x070007;
        //	c.u |= (c.u >> 6) & 0x000300;

        color.b = (c.b << 3) | (c.b >> 2);
        color.g = (c.g << 2) | (c.g >> 4);
        color.r = (c.r << 3) | (c.r >> 2);
        color.a = 0xFF;

        return color;
    }

    inline Vector4 toVector4(Color32 c)
    {
        const float scale = 1.0f / 255.0f;
        return Vector4(c.r * scale, c.g * scale, c.b * scale, c.a * scale);
    }

} // nv namespace

#endif // NV_MATH_COLOR_H