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fpsunflower/nanoexr.cpp

Last active December 9, 2021 14:42
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Revisions

  1. fpsunflower revised this gist Jul 18, 2021. 1 changed file with 1 addition and 1 deletion.
    2 changes: 1 addition & 1 deletion nanoexr.cpp
    View file
    Original file line number Diff line number Diff line change
    @@ -12,7 +12,7 @@ struct Exr {
    void C(const char* name) { S(name);L(2);I(1);I(1); }
    Exr(const char* fn, int w, int h, const float* c) : f(fopen(fn, "w")) {
    I(20000630);I(514); // magic/version/tiled
    S("channels");S("chlist");I(55);C("R");C("G");C("B");B(0);
    S("channels");S("chlist");I(55);C("B");C("G");C("R");B(0);
    S("compression");S("compression");I(1);B(0);
    S( "dataWindow");S("box2i");I(16);I(0);I(0);I(w-1);I(h-1);
    S("displayWindow");S("box2i");I(16);I(0);I(0);I(w-1);I(h-1);
  2. fpsunflower created this gist Sep 24, 2014.
    55 changes: 55 additions & 0 deletions nanoexr.cpp
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,55 @@
    // c++ -o nanoexr nanoexr.cpp && ./nanoexr /tmp/foo.exr
    #include <cstdio>

    // writes a tiled OpenEXR file from a float RGB buffer
    struct Exr {
    FILE* f; enum{TS=64}; ~Exr() { fclose(f); }
    void B(unsigned char i) { fputc(i,f); }
    void I(unsigned int i) { fwrite(&i,1,4,f); }
    void L(unsigned long long i) { fwrite(&i,1,8,f); }
    void F(float x) { fwrite(&x,1,4,f); }
    void S(const char* str) { fputs(str,f);B(0); }
    void C(const char* name) { S(name);L(2);I(1);I(1); }
    Exr(const char* fn, int w, int h, const float* c) : f(fopen(fn, "w")) {
    I(20000630);I(514); // magic/version/tiled
    S("channels");S("chlist");I(55);C("R");C("G");C("B");B(0);
    S("compression");S("compression");I(1);B(0);
    S( "dataWindow");S("box2i");I(16);I(0);I(0);I(w-1);I(h-1);
    S("displayWindow");S("box2i");I(16);I(0);I(0);I(w-1);I(h-1);
    S("lineOrder");S("lineOrder");I(1);B(2);
    S("pixelAspectRatio");S("float");I(4);F(1.0f);
    S("screenWindowCenter");S("v2f");I(8);F(0.0f);F(0.0f);
    S("screenWindowWidth");S("float");I(4);F(1.0f);
    S("tiles");S("tiledesc");I(9);I(TS);I(TS);B(0);B(0);
    int tx = (w + TS - 1) / TS, ty = (h + TS - 1) / TS;
    long off = ftell(f) + tx * ty * 8; float out[TS * 3];
    for (int k = 2; k--;) for (int y = 0; y < h; y += TS)
    for (int x = 0; x < w; x += TS) {
    int tw = w-x > TS ? TS : w-x;
    int th = h-y > TS ? TS : h-y, sz=tw*th*12;
    if (k) { L(off); off += 20 + sz; continue; }
    I(x / TS);I(y / TS);I(0);I(0);I(sz);
    for (int ty = 0; ty < th; ty++) {
    const float* in = c + 3 * (x+w*(y+ty));
    for (int tx = 0; tx < tw; tx++)
    out[ tx] = in[3*tx+2],
    out[ tw+tx] = in[3*tx+1],
    out[tw+tw+tx] = in[3*tx+0];
    fwrite(out, 12, tw, f);
    }
    }
    }
    };

    // example usage
    int main(int argc, const char** argv) {
    int w = 640, h = 480;
    float* image = new float[3 * w * h];
    for (int y = 0, idx = 0; y < h; y++)
    for (int x = 0; x < w; x++, idx += 3)
    image[idx + 0] = float(x) / w,
    image[idx + 1] = float(y) / h,
    image[idx + 2] = 0;
    Exr(argc < 2 ? "/tmp/test.exr" : argv[1], w, h, image);
    delete [] image;
    }