HYPER MIKAN BOX

文書の過去の版を表示しています。

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<codeprism lang=cpp el=true css=full> #include <raylib.h>

#include <cmath> #include <iterator> #include <vector>

#include “vmath.h”

int const Cw = 600; int const Ch = 600; float const Vw = 1.0; float const Vh = 1.0; float ProjectionPlaneZ = 1.0;

using vec2 = vmath::vec2<float>; using vec3 = vmath::vec3<float>;

void PutPixel(int x, int y, Color const &color) {

  DrawPixel(x + Cw / 2, -y + Ch / 2, color);

}

template <typename Iter>

  requires std::output_iterator<Iter, float>

void Interpolate(int i0, float d0, int i1, float d1, Iter out) {

  if (i0 == i1) {
      *out = d0;
      return;
  }

  auto a = (d1 - d0) / (i1 - i0);
  auto d = d0;

  for (int i = i0; i <= i1; ++i) {
      *out++ = d;
      d += a;
  }

}

void DrawLine(vec2 const &p0, vec2 const &p1, Color const &color) {

  auto x0 = p0.x;
  auto y0 = p0.y;
  auto x1 = p1.x;
  auto y1 = p1.y;

  if (std::abs(x1 - x0) > std::abs(y1 - y0)) {
      if (x0 > x1) {
          std::swap(x0, x1);
          std::swap(y0, y1);
      }
      auto i0 = static_cast<int>(std::floor(x0));
      auto i1 = static_cast<int>(std::floor(x1));
      auto ys = std::vector<float>(i1 - i0 + 1);
      Interpolate(i0, y0, i1, y1, ys.begin());
      for (int i = i0; i <= i1; ++i) {
          PutPixel(i, ys[i - i0], color);
      }
  } else {
      if (y0 > y1) {
          std::swap(y0, y1);
          std::swap(x0, x1);
      }
      auto i0 = static_cast<int>(std::floor(y0));
      auto i1 = static_cast<int>(std::floor(y1));
      auto xs = std::vector<float>(i1 - i0 + 1);
      Interpolate(i0, x0, i1, x1, xs.begin());
      for (int i = i0; i <= i1; ++i) {
          PutPixel(xs[i - i0], i, color);
      }
  }

}

vec2 ViewportToCanvas(float x, float y) {

  return {x * Cw / Vw, y * Ch / Vh};

}

vec2 ProjectVertex(vec3 const &v) {

  return ViewportToCanvas(v.x * ProjectionPlaneZ / v.z,
                          v.y * ProjectionPlaneZ / v.z);

}

int main() {

  InitWindow(Cw, Ch, "Perspective Projection");

  // front
  auto vAf = vec3{-1, 1, 4};
  auto vBf = vec3{1, 1, 4};
  auto vCf = vec3{1, -1, 4};
  auto vDf = vec3{-1, -1, 4};

  // back
  auto vAb = vec3{-1, 1, 6};
  auto vBb = vec3{1, 1, 6};
  auto vCb = vec3{1, -1, 6};
  auto vDb = vec3{-1, -1, 6};

  while (!WindowShouldClose()) {
      BeginDrawing();

      ClearBackground(WHITE);

      DrawLine(ProjectVertex(vAf), ProjectVertex(vBf), BLUE);
      DrawLine(ProjectVertex(vBf), ProjectVertex(vCf), BLUE);
      DrawLine(ProjectVertex(vCf), ProjectVertex(vDf), BLUE);
      DrawLine(ProjectVertex(vDf), ProjectVertex(vAf), BLUE);

      DrawLine(ProjectVertex(vAb), ProjectVertex(vBb), RED);
      DrawLine(ProjectVertex(vBb), ProjectVertex(vCb), RED);
      DrawLine(ProjectVertex(vCb), ProjectVertex(vDb), RED);
      DrawLine(ProjectVertex(vDb), ProjectVertex(vAb), RED);

      DrawLine(ProjectVertex(vAf), ProjectVertex(vAb), GREEN);
      DrawLine(ProjectVertex(vBf), ProjectVertex(vBb), GREEN);
      DrawLine(ProjectVertex(vCf), ProjectVertex(vCb), GREEN);
      DrawLine(ProjectVertex(vDf), ProjectVertex(vDb), GREEN);

      EndDrawing();
  }

} <codeprism>