From 25b08ce8bbc34c82558b86111f07fb88bf3b19dd Mon Sep 17 00:00:00 2001
From: Lucas Fryzek <lucas.fryzek@gmail.com>
Date: Mon, 20 Feb 2023 14:32:27 -0500
Subject: Update small code issues for triangles

---
 notes/rasterizing-triangles.md | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

(limited to 'notes')

diff --git a/notes/rasterizing-triangles.md b/notes/rasterizing-triangles.md
index 354c4fa..73acb33 100644
--- a/notes/rasterizing-triangles.md
+++ b/notes/rasterizing-triangles.md
@@ -1,7 +1,7 @@
 ---
 title: "Rasterizing Triangles"
 date: "2022-04-03"
-last_edit: "2022-10-30"
+last_edit: "2023-02-20"
 status: 2
 cover_image: "/assets/2022-04-03-rasterizing-triangles/Screenshot-from-2022-04-03-13-43-13.png"
 ---
@@ -72,7 +72,7 @@ func edge(x, y, xi, yi, dXi, dYi)
 func draw_triangle(x0, y0, x1, y1, x2, y2, v0, v1, v2):
     dX0 = x0 - x2
     dX1 = x1 - x0
-    dX2 = x2 - x2
+    dX2 = x2 - x1
     dY0 = y0 - y2
     dY1 = y1 - y0
     dY2 = y2 - y1
@@ -96,20 +96,20 @@ func draw_triangle(x0, y0, x1, y1, x2, y2, v0, v1, v2):
         for x = 0 to screen_width:
             if(e0 >= 0 && e1 >= 0 && e2 >= 0)
                 draw_pixel(x, y, v)
-        e0 = e0 + dY0
-        e1 = e1 + dY1
-        e2 = e2 + dY2
-        v = v + dYV
-
-    e0 = starting_e0 - dX0
-    e1 = starting_e1 - dX1
-    e2 = starting_e2 - dX2
-    v = starting_v - dXV
-
-    starting_e0 = e0
-    starting_e1 = e1
-    starting_e2 = e2
-    starting_v = v
+            e0 = e0 + dY0
+            e1 = e1 + dY1
+            e2 = e2 + dY2
+            v = v + dYV
+
+        e0 = starting_e0 - dX0
+        e1 = starting_e1 - dX1
+        e2 = starting_e2 - dX2
+        v = starting_v - dXV
+
+        starting_e0 = e0
+        starting_e1 = e1
+        starting_e2 = e2
+        starting_v = v
 ```
 
 Now this pseudo code is not the most efficient as it will iterate over the entire screen to draw one triangle, but it provides a starting basis to show how to use these Pineda properties to calculate per vertex values. One thing to note if you do implement this is, if you use fixed point arithmetic, be careful to insure you have enough precision to calculate all of these values with overflow or underflow. This was an issue I ran into running out of precision when I did the divide by the area.
-- 
cgit v1.2.3