Platform dependent fixes

[Xin-888]

Hello, here are the fixes I needed to properly generate the displacement textures on windows (I compiled with Code::Blocks MinGW x64 and tested it with an older graphics card):

• In

  dhdm/src/diff.cc

  Line 121 in eeb0ce2

  glm::dvec3 d0, d1, d2;

  you need to make sure to value initialize the dvec3s, there is no guarantee that they will be value initialized.

• In

  dhdm/src/render.cc

  Line 235 in eeb0ce2

  glReadnPixels(0, 0, width, width, GL_RGB, GL_UNSIGNED_SHORT, data.size() * sizeof(Pixel), data.data());

  you could use the older version "glReadPixels(0, 0, width, width, GL_RGB, GL_UNSIGNED_SHORT, data.data());" to avoid crashes with older cards that don't support the latest versions of OpenGL.

• Also around

  dhdm/src/render.cc

  Line 125 in eeb0ce2
  you have to make sure to call "glViewport(0, 0, width, width);", since there is no guarantee that glfwCreateWindow() will have the supplied resolution, so the mapping to screen coordinates can end up buggy once the framebuffer is set up.

• I personally didn't experience the following issue, but it's a good practice to complete the framebuffer. Something like:

    GLuint renderBuffer;
    glGenRenderbuffers(1, &renderBuffer);
    glBindRenderbuffer(GL_RENDERBUFFER, renderBuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, width, width);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, renderBuffer);
    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        throw std::runtime_error("framebuffer is not complete.");
    glDisable(GL_DEPTH_TEST);
  

• While we are at it, a useful qol change would be to keep track of the most positive and most negative pixel values to help detect scaling issues. Something like (in diff.cc):

    ...
    
    auto maxp = std::max(displ2.x, std::max(displ2.y, displ2.z));
    maxDispl_positive = std::max(maxDispl_positive, maxp);
  
    auto maxn = std::min(displ2.x, std::min(displ2.y, displ2.z));
    maxDispl_negative = std::min(maxDispl_negative, maxn);
            
    ...
            
    std::cerr << "Most positive pixel component value: " << (maxDispl_positive * scale + 0.5) * 255.0 << "\n";
    std::cerr << "Most negative pixel component value: " << (maxDispl_negative * scale + 0.5) * 255.0 << "\n";
  

[edolstra]

Thanks @Xin-888, I've applied your suggestions!

[Xin-888]

Thanks for the quick fixes @edolstra . By the way, I think there is a typo in

dhdm/src/diff.cc

Line 100 in e488f37

if (std::max(maxPos, abs(maxPos)) > 1e-6) {

, you meant "abs(maxNeg)" not "abs(maxPos)".

Thanks again.

[edolstra]

Thanks, fixed!