cuda-samples/Samples/7_libNVVM/common/include/DDSWriter.h

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#ifndef DDSWRITER_H
#define DDSWRITER_H

#include <fstream>

typedef int DWORD;

/// DDS File Structures
struct DDSPixelFormat
{
    DWORD Size;
    DWORD Flags;
    DWORD FourCC;
    DWORD RGBBitCount;
    DWORD RBitMask;
    DWORD GBitMask;
    DWORD BBitMask;
    DWORD ABitMask;
};

struct DDSHeader
{
    DWORD          Size;
    DWORD          Flags;
    DWORD          Height;
    DWORD          Width;
    DWORD          PitchOrLinearSize;
    DWORD          Depth;
    DWORD          MipMapCount;
    DWORD          Reserved1[11];
    DDSPixelFormat PixelFormat;
    DWORD          Caps;
    DWORD          Caps2;
    DWORD          Caps3;
    DWORD          Caps4;
    DWORD          Reserved2;
};

#define DDPF_ALPHAPIXELS 0x1
#define DDPF_RGB         0x40

#define DDSD_CAPS        0x1
#define DDSD_HEIGHT      0x2
#define DDSD_WIDTH       0x4
#define DDSD_PIXELFORMAT 0x1000

#define DDSCAPS_TEXTURE 0x1000


/// WriteDDS - Writes image data to a .dds file.  The data is expected to be
/// (R, G, B, A) tuples of 32-bit floating-point data of dimensions
/// width X height.  The floating-point data should be normalized to [0,1] and
/// will be scaled to a [0, 255] 8-bit value.
void writeDDS(const char *filename, const float *data, unsigned width, unsigned height)
{
    // Write out the result as a .dds file
    // This is a quick and dirty DDS writer
    DDSHeader header;
    memset(&header, 0, sizeof(DDSHeader));

    header.Size              = sizeof(DDSHeader);
    header.Flags             = DDSD_CAPS | DDSD_HEIGHT | DDSD_WIDTH | DDSD_PIXELFORMAT;
    header.Height            = height;
    header.Width             = width;
    header.PitchOrLinearSize = width * 4;
    header.Caps              = DDSCAPS_TEXTURE;

    header.PixelFormat.Size        = sizeof(DDSPixelFormat);
    header.PixelFormat.Flags       = DDPF_RGB | DDPF_ALPHAPIXELS;
    header.PixelFormat.RGBBitCount = 32;
    header.PixelFormat.ABitMask    = 0xFF000000;
    header.PixelFormat.RBitMask    = 0x00FF0000;
    header.PixelFormat.GBitMask    = 0x0000FF00;
    header.PixelFormat.BBitMask    = 0x000000FF;

    std::ofstream str(filename, std::ios::binary);
    int           magic = 0x20534444;
    str.write((const char *)&magic, 4);
    str.write((const char *)&header, sizeof(header));
    for (unsigned j = 0; j < height; ++j) {
        for (unsigned i = 0; i < width; ++i) {
            unsigned char r, g, b, a;
            r = (unsigned char)(data[j * width * 4 + i * 4 + 0] * 255.0);
            g = (unsigned char)(data[j * width * 4 + i * 4 + 1] * 255.0);
            b = (unsigned char)(data[j * width * 4 + i * 4 + 2] * 255.0);
            a = (unsigned char)(data[j * width * 4 + i * 4 + 3] * 255.0);
            str.write((const char *)&b, 1);
            str.write((const char *)&g, 1);
            str.write((const char *)&r, 1);
            str.write((const char *)&a, 1);
        }
    }
    str.close();
}

#endif