message: Copied cv::getAffineTransform locally
  And use the copied version.
diff: #include "Eigen/Core"
  #include "opencv2/core/core.hpp"
  -#include "opencv2/imgproc/imgproc.hpp"
  #include <tuple>
  #include <cassert>
  namespace eos {
  namespace render {
  +/* This function is copied from OpenCV, originally under BSD licence.
  + * imgwarp.cpp from OpenCV-3.2.0.
  + *
  + * Calculates coefficients of affine transformation
  + * which maps (xi,yi) to (ui,vi), (i=1,2,3):
  + *
  + * ui = c00*xi + c01*yi + c02
  + *
  + * vi = c10*xi + c11*yi + c12
  + *
  + * Coefficients are calculated by solving linear system:
  + * / x0 y0 1 0 0 0 \ /c00\ /u0\
  + * | x1 y1 1 0 0 0 | |c01| |u1|
  + * | x2 y2 1 0 0 0 | |c02| |u2|
  + * | 0 0 0 x0 y0 1 | |c10| |v0|
  + * | 0 0 0 x1 y1 1 | |c11| |v1|
  + * \ 0 0 0 x2 y2 1 / |c12| |v2|
  + *
  + * where:
  + * cij - matrix coefficients
  + */
  +cv::Mat getAffineTransform( const cv::Point2f src[], const cv::Point2f dst[] )
  +{
  + using cv::Mat;
  + Mat M(2, 3, CV_64F);
  + Mat X(6, 1, CV_64F, M.ptr());
  + double a[6*6], b[6];
  + Mat A(6, 6, CV_64F, a), B(6, 1, CV_64F, b);
  +
  + for( int i = 0; i < 3; i++ )
  + {
  + int j = i*12;
  + int k = i*12+6;
  + a[j] = a[k+3] = src[i].x;
  + a[j+1] = a[k+4] = src[i].y;
  + a[j+2] = a[k+5] = 1;
  + a[j+3] = a[j+4] = a[j+5] = 0;
  + a[k] = a[k+1] = a[k+2] = 0;
  + b[i*2] = dst[i].x;
  + b[i*2+1] = dst[i].y;
  + }
  +
  + cv::solve( A, B, X );
  + return M;
  +};
  +
  /**
  * The interpolation types that can be used to map the
  * texture from the original image to the isomap.
  @@ -229,7 +274,7 @@ inline core::Image4u extract_texture(const core::Mesh& mesh, Eigen::Matrix<float
  // We use the inverse/ backward mapping approach, so we want to find the corresponding texel (texture-pixel) for each pixel in the isomap
  // Get the inverse Affine Transform from original image: from dst (pixel in isomap) to src (in image)
  - Mat warp_mat_org_inv = cv::getAffineTransform(dst_tri, src_tri); // I think I can copy the code to this into the repo temporarily, if it's not too complicated...
  + Mat warp_mat_org_inv = render::getAffineTransform(dst_tri, src_tri); // I think I can copy the code to this into the repo temporarily, if it's not too complicated...
  warp_mat_org_inv.convertTo(warp_mat_org_inv, CV_32FC1);
  // We now loop over all pixels in the triangle and select, depending on the mapping type, the corresponding texel(s) in the source image
  