MeshGeneratorCommon.h

#pragma once
 
#include "Context.h"
 
#include "Resources/VertexFormats.h"
#include "Resources/Mesh.h"
 
#include <glm/vec4.hpp>
 
#include <algorithm>
 
using namespace Cogs::Core;
 
namespace
{
  int refinementLevel(int samples, int levels, int maxSamples)
  {
    samples = std::max(1, samples); // refinement level less than 1 is illegal (and log breaks down)
    int la = int(std::floor(levels * (std::log2(float(samples)) / std::log(float(maxSamples))) + 0.5f));
    int lb = samples - 1; // linear function for small values, to avoid skipping levels
    return std::min(std::min(la, lb), levels - 1);
  }
 
  int samplesFromLevel(int level, int levels, int maxSamples)
  {
    int sa = std::min(maxSamples, int(std::floor(std::pow(maxSamples, float(level) / float(levels)))));
    int sb = level + 1;
    return std::max(sa, sb);
  }
 
  template<typename VectorIterator>
  Cogs::Geometry::BoundingBox computeBoundingBoxFromVertexFormat(VectorIterator start, VectorIterator end)
  {
    Cogs::Geometry::BoundingBox box;
 
    while (start != end) {
      box.expand(start->position);
      ++start;
    }
 
    return box;
  }
 
  void coordSysFactory(Mesh * mesh, const ShapeDefinition & definition)
  {
    //Assumes XY plane, ignores Z
    auto & s = definition.size;
 
    std::vector<PositionColorVertex> vertexData = {
      { glm::vec4(0.f, 0.f, 0.f, 1.f), glm::vec4(1.f, 0.f, 0.f, 1.f) },
      { glm::vec4(s.x, 0.f, 0.f, 1.f), glm::vec4(1.f, 0.f, 0.f, 1.f) },
 
      { glm::vec4(0.f, 0.f, 0.f, 1.f), glm::vec4(0.f, 1.f, 0.f, 1.f) },
      { glm::vec4(0.f, s.y, 0.f, 1.f), glm::vec4(0.f, 1.f, 0.f, 1.f) },
 
      { glm::vec4(0.f, 0.f, 0.f, 1.f), glm::vec4(0.f, 0.f, 1.f, 1.f) },
      { glm::vec4(0.f, 0.f, s.z, 1.f), glm::vec4(0.f, 0.f, 1.f, 1.f) },
    };
 
    mesh->setVertexData(vertexData.data(), vertexData.size());
    mesh->primitiveType = Cogs::PrimitiveType::LineList;
    mesh->setBounds(computeBoundingBoxFromVertexFormat(vertexData.begin(), vertexData.end()));
  }
 
}