Optimize the code according to: ssloy/tinyrenderer#28.

zfengyan · May 10, 2022 · f6ac2c6 · f6ac2c6
1 parent b48c66b
commit f6ac2c6
Showing 1 changed file with 18 additions and 9 deletions.
diff --git a/src/main.cpp b/src/main.cpp
@@ -15,23 +15,32 @@ void line(int x0, int y0, int x1, int y1, TGAImage& image, TGAColor color) {
  std::swap(x0, x1);
  std::swap(y0, y1);
  }
+
  int dx = x1 - x0;
  int dy = y1 - y0;
  int derror2 = std::abs(dy) * 2;
  int error2 = 0;
  int y = y0;
- for (int x = x0; x <= x1; x++) {
- if (steep) {
+ int y_increment = y1 > y0 ? 1 : -1;
+
+ if (steep) {
+ for (int x = x0; x <= x1; ++x) {
  image.set(y, x, TGAColor(255, 1));
+ error2 += derror2;
+ if (error2 > dx) {
+ y += y_increment;
+ error2 -= dx * 2;
+ }
  }
- else {
+ }
+ else {
+ for (int x = x0; x <= x1; ++x) {
  image.set(x, y, TGAColor(255, 1));
- }
- error2 += derror2;
-
- if (error2 > dx) {
- y += (y1 > y0 ? 1 : -1);
- error2 -= dx * 2;
+ error2 += derror2;
+ if (error2 > dx) {
+ y += y_increment;
+ error2 -= dx * 2;
+ }
  }
  }
 }