OOSaveEXRSnapshot.cpp

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#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <vector>
 
extern "C" {
    int SaveEXRSnapshot(const char* outfilename, int width, int height, const float* rgb);
}
 
#ifdef WIN32
#define TINYEXR_IMPLEMENTATION
#include "tinyexr.h"
 
int SaveEXRSnapshot(const char* outfilename, int width, int height, const float* rgb)
{
    EXRHeader header;
    InitEXRHeader(&header);
    
    EXRImage image;
    InitEXRImage(&image);
    
    image.num_channels = 3;
    
    std::vector<float> images[3];
    images[0].resize(width * height);
    images[1].resize(width * height);
    images[2].resize(width * height);
    
    for (int i = 0; i < width * height; i++)
    {
        images[0][i] = rgb[3*i+0];
        images[1][i] = rgb[3*i+1];
        images[2][i] = rgb[3*i+2];
    }
    
    float* image_ptr[3];
    image_ptr[0] = &(images[2].at(0)); // B
    image_ptr[1] = &(images[1].at(0)); // G
    image_ptr[2] = &(images[0].at(0)); // R
    
    image.images = (unsigned char**)image_ptr;
    image.width = width;
    image.height = height;
    
    header.num_channels = 3;
    header.compression_type = TINYEXR_COMPRESSIONTYPE_ZIP;
    header.channels = (EXRChannelInfo *)malloc(sizeof(EXRChannelInfo) * header.num_channels); 
 
    // sign our snapshot
    header.num_custom_attributes = 1;
    header.custom_attributes = static_cast<EXRAttribute *>(malloc(sizeof(EXRAttribute)));
    strncpy(header.custom_attributes[0].name, "signature", 255);
    strncpy(header.custom_attributes[0].type, "string", 255);
    std::time_t timestamp;
    std::time(&timestamp);
    char signatureStringIntro[255] = "Generated by Oolite ";
    char *signatureString = strcat(signatureStringIntro, std::ctime(&timestamp));
    // ctime adds a newline at the end of the string, strip it
    signatureString[strlen(signatureString) - 1] = '\0';
    header.custom_attributes[0].value = reinterpret_cast<uint8_t *>(signatureString);
    header.custom_attributes[0].size  = strlen(signatureString);
    
    // Must be BGR(A) order, since most of EXR viewers expect this channel order.
    strncpy(header.channels[0].name, "B", 255); header.channels[0].name[strlen("B")] = '\0';
    strncpy(header.channels[1].name, "G", 255); header.channels[1].name[strlen("G")] = '\0';
    strncpy(header.channels[2].name, "R", 255); header.channels[2].name[strlen("R")] = '\0';
    
    header.pixel_types = (int *)malloc(sizeof(int) * header.num_channels); 
    header.requested_pixel_types = (int *)malloc(sizeof(int) * header.num_channels);
    for (int i = 0; i < header.num_channels; i++)
    {
        header.pixel_types[i] = TINYEXR_PIXELTYPE_FLOAT; // pixel type of input image
        header.requested_pixel_types[i] = TINYEXR_PIXELTYPE_HALF; // pixel type of output image to be stored in .EXR
    }
    
    const char* err;
    int ret = SaveEXRImageToFile(&image, &header, outfilename, &err);
    if (ret != TINYEXR_SUCCESS)
    {
        fprintf(stderr, "Save EXR err: %s\n", err);
    }
    
    free(header.channels);
    free(header.pixel_types);
    free(header.requested_pixel_types);
    
    return ret;
}
#else // Linux EXR snaphsots not supported yet
int SaveEXRSnapshot(const char* outfilename, int width, int height, const float* rgb)
{
    fprintf(stderr, "EXR Snapshot not supported yet under Linux!\n");
    return 0;
}
#endif