From 70e503a4eb4f241ee955714baf23584ab22f7c97 Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Sun, 9 Feb 2025 15:23:01 -0600
Subject: [PATCH] improve vertex order and triangle generation

---
 Makefile |   2 +
 main.cpp | 121 +++++++++++++++++++++++++++++--------------------------
 2 files changed, 65 insertions(+), 58 deletions(-)

diff --git a/Makefile b/Makefile
index f4f3d87..c73a5a5 100644
--- a/Makefile
+++ b/Makefile
@@ -9,6 +9,8 @@ DEBUG = -g -gdwarf-5
 
 CFLAGS += -Wall -Werror -Wfatal-errors
 CFLAGS += -Wno-error=unused-function
+CFLAGS += -Wno-error=unused-but-set-variable
+CFLAGS += -Wno-error=unused-variable
 CFLAGS += -std=c++23
 CFLAGS += -I$(SDL)/include -D_REENTRANT
 CFLAGS += $(shell pkg-config --cflags freetype2)
diff --git a/main.cpp b/main.cpp
index c1b9421..09473ac 100644
--- a/main.cpp
+++ b/main.cpp
@@ -478,21 +478,46 @@ void render_tri(SDL_Renderer * renderer,
   render_line_vtx(renderer, c, a);
 }
 
-struct tri generate_tri(struct edge * silhouette,
-                        int * order,
-                        int o0,
-                        int o1)
+static const vec3 colors[] = {
+  {1, 0, 0}, // red
+  {1, 0.5, 0}, // orange
+  {1, 1, 0}, // yellow
+  {0, 1, 0}, // green
+  {0, 1, 1}, // cyan
+  {0.5, 0, 1}, // purple
+};
+
+void render_perimeter_wall(SDL_Renderer * renderer,
+                           const vec3 * position,
+                           int a,
+                           int b,
+                           int c,
+                           int d,
+                           int e,
+                           int f
+                           )
 {
-  struct tri tri;
-  tri.a = silhouette[order[o0]].a;
-  tri.b = silhouette[order[o0]].b;
-  if (silhouette[order[o0]].a == silhouette[order[o1]].a ||
-      silhouette[order[o0]].b == silhouette[order[o1]].a) {
-    tri.c = silhouette[order[o1]].b;
-  } else {
-    tri.c = silhouette[order[o1]].a;
-  }
-  return tri;
+  float scale = 0.5f;
+
+  vec3 av = transform_vertex(position[a], scale);
+  vec3 bv = transform_vertex(position[b], scale);
+  vec3 cv = transform_vertex(position[c], scale);
+  vec3 dv = transform_vertex(position[d], scale);
+  vec3 ev = transform_vertex(position[e], scale);
+  vec3 fv = transform_vertex(position[f], scale);
+
+  assert(SDL_SetRenderDrawColorFloat(renderer, colors[0].x, colors[0].y, colors[0].z, 1));
+  render_line_vtx(renderer, av, bv);
+  assert(SDL_SetRenderDrawColorFloat(renderer, colors[1].x, colors[1].y, colors[1].z, 1));
+  render_line_vtx(renderer, bv, cv);
+  assert(SDL_SetRenderDrawColorFloat(renderer, colors[2].x, colors[2].y, colors[2].z, 1));
+  render_line_vtx(renderer, cv, dv);
+  assert(SDL_SetRenderDrawColorFloat(renderer, colors[3].x, colors[3].y, colors[3].z, 1));
+  render_line_vtx(renderer, dv, ev);
+  assert(SDL_SetRenderDrawColorFloat(renderer, colors[4].x, colors[4].y, colors[4].z, 1));
+  render_line_vtx(renderer, ev, fv);
+  assert(SDL_SetRenderDrawColorFloat(renderer, colors[5].x, colors[5].y, colors[5].z, 1));
+  render_line_vtx(renderer, fv, av);
 }
 
 void render_silhouette(SDL_Renderer * renderer,
@@ -516,66 +541,46 @@ void render_silhouette(SDL_Renderer * renderer,
 
   assert(ix == 6);
 
-  int order[6];
-  order[0] = 0;
-  int order_ix = 1;
-  int vtx = silhouette[0].b;
+  int last_ix = 0;
+  int order_ix = 0;
+  int order_vtx[6];
+  order_vtx[order_ix++] = silhouette[0].b;
 
-  // calculate edge ordering
+  // calculate vertex ordering
   while (order_ix < 6) {
     for (int i = 1; i < 6; i++) {
-      if (i == order[order_ix - 1])
+      if (i == last_ix)
         continue;
 
-      if (silhouette[i].a == vtx) {
-        vtx = silhouette[i].b;
-        order[order_ix++] = i;
+      int last_vtx = order_vtx[order_ix - 1];
+      if (last_vtx == silhouette[i].a) {
+        last_ix = i;
+        order_vtx[order_ix++] = silhouette[i].b;
         break;
       }
-      if (silhouette[i].b == vtx) {
-        vtx = silhouette[i].a;
-        order[order_ix++] = i;
+      if (last_vtx == silhouette[i].b) {
+        last_ix = i;
+        order_vtx[order_ix++] = silhouette[i].a;
         break;
       }
     }
   }
 
-  assert(order_ix == 6);
-
-  const vec3 colors[] = {
-    {1, 0, 0}, // red
-    {1, 0.5, 0}, // orange
-    {1, 1, 0}, // yellow
-    {0, 1, 0}, // green
-    {0, 1, 1}, // cyan
-    {0.5, 0, 1}, // purple
-  };
-
   /*
-  for (int i = 0; i < 6; i++) {
-    assert(SDL_SetRenderDrawColorFloat(renderer, colors[i].x, colors[i].y, colors[i].z, 1));
-
-    vec3 ap = position[silhouette[order[i]].a];
-    vec3 bp = position[silhouette[order[i]].b];
-
-    float scale = 0.5f;
-    vec3 av = transform_vertex(ap, scale);
-    vec3 bv = transform_vertex(bp, scale);
-    render_line_vtx(renderer, av, bv);
-  }
+  render_perimeter_wall(renderer, position,
+                        order_vtx[0],
+                        order_vtx[1],
+                        order_vtx[2],
+                        order_vtx[3],
+                        order_vtx[4],
+                        order_vtx[5]);
   */
 
   // render triangulation
-  /*
-    {0.a, 0.b}, {1.a, 1.b}, {0._, 1._}
-    {2.a, 2.b}, {3.a, 3.b}, {2._, 3._}
-    {4.a, 4.b}, {5.a, 5.b}, {4._, 5._}
-    {0._, 1._}, {2._, 3._}, {4._, 5._}
-   */
-  struct tri q = generate_tri(silhouette, order, 0, 1);
-  struct tri r = generate_tri(silhouette, order, 2, 3);
-  struct tri s = generate_tri(silhouette, order, 4, 5);
-  struct tri t = {q.c, r.c, s.c};
+  struct tri q = {order_vtx[0], order_vtx[1], order_vtx[2]};
+  struct tri r = {order_vtx[2], order_vtx[3], order_vtx[4]};
+  struct tri s = {order_vtx[4], order_vtx[5], order_vtx[0]};
+  struct tri t = {order_vtx[0], order_vtx[2], order_vtx[4]};
 
   render_tri(renderer, position, colors[1], q);
   render_tri(renderer, position, colors[2], r);