C++グラフィックスプログラミングアルゴリズムの精緻な解析

void drawLine(int x1, int y1, int x2, int y2) {
  int dx = x2 - x1;
  int dy = y2 - y1;
  int d = 2 * dy - dx;
  int y = y1;
  for (int x = x1; x <= x2; x++) {
    plot(x, y);
    if (d < 0) {
      d += 2 * dy;
    } else {
      d += 2 * (dy - dx);
      y++;
    }
  }
}

void fill(int x1, int y1, int x2, int y2, int color) {
  for (int y = y1; y <= y2; y++) {
    int x_min = INT_MAX, x_max = INT_MIN;
    for (int x = x1; x <= x2; x++) {
      if (isInsideBoundary(x, y)) {
        x_min = min(x_min, x);
        x_max = max(x_max, x);
      }
    }
    for (int x = x_min; x <= x_max; x++) {
      plot(x, y, color);
    }
  }
}

void scanFill(int x1, int y1, int x2, int y2, int color) {
  int edgeTable[MAX_SIZE][2];  // 存储轮廓边
  int edgeCount = 0;

  // 构建边表
  for (int x = x1; x <= x2; x++) {
    int y_min = INT_MAX, y_max = INT_MIN;
    for (int y = y1; y <= y2; y++) {
      if (isInsideBoundary(x, y)) {
        y_min = min(y_min, y);
        y_max = max(y_max, y);
      }
    }
    if (y_min != INT_MAX) {
      edgeTable[edgeCount][0] = x;
      edgeTable[edgeCount][1] = y_min;
      edgeCount++;
      edgeTable[edgeCount][0] = x;
      edgeTable[edgeCount][1] = y_max;
      edgeCount++;
    }
  }

  // 扫描填充
  for (int j = 0; j < edgeCount; j += 2) {
    for (int x = edgeTable[j][0]; x <= edgeTable[j + 1][0]; x++) {
      plot(x, edgeTable[j][1], color);
      plot(x, edgeTable[j + 1][1], color);
    }
  }
}