contour-creator/src/HeightMap.cpp

#include <iostream>
#include <stdexcept>

#include <gdal/gdal.h>
#include "gdal/gdal_priv.h"
#include <gdal/gdal_frmts.h>

#include "contour_creator.hh"


HeightMap::HeightMap(const char* filepath) 
{
    // Open the file with gdal:
    const GDALAccess eAccess = GA_ReadOnly;
    GDALDatasetUniquePtr file;
    GDALRegister_GTiff();
    file = GDALDatasetUniquePtr(GDALDataset::FromHandle(GDALOpen( filepath, eAccess )));
    if( !file )
    {
        throw std::runtime_error("Could not open tif file!");
    }
    
    // The heigthmap only has one band
    auto band = file->GetBands()[0];
    
    // write the attrributes
    this->width = band->GetXSize();
    this->height = band->GetYSize();
    this->min = band->GetMinimum();
    this->max = band-> GetMaximum();
    this->reference_system = *(file->GetSpatialRef());
    
    this->data = (float *) CPLMalloc(sizeof(float)*width*height);
    CPLErr error = band->RasterIO( GF_Read, 0, 0, width, height,
                    this->data, width, height, GDT_Float32,
                    0, 0 );
    if (error) { throw std::runtime_error("Could not read tif file!"); }
    band->FlushCache();
}
float HeightMap::get_pixel(int x, int y)
{
    // all the pixels are in an array of floats from left to right, top to bottom
    int offset = ((this->width * y) + x);
    //std::cout << "  offset: " << offset << " " << x << ","<< y;
    return *(this->data + offset);
}