From 5f2e7e440a4fb6aab04a4970720efe7d8246911c Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Sat, 19 Apr 2025 18:24:31 -0500
Subject: [PATCH] collision: use the complete transformation matrix

---
 src/haunted_mansion.cpp | 26 +++++++++++---------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/src/haunted_mansion.cpp b/src/haunted_mansion.cpp
index 1e21cc8..bc738f5 100644
--- a/src/haunted_mansion.cpp
+++ b/src/haunted_mansion.cpp
@@ -777,26 +777,22 @@ bool collided[256] = {};
 
 bool line_has_collision(vec3 a1, vec3 a2, const mat4x4& model_trans, const mat4x4& screen)
 {
+  mat4x4 trans = screen * model_trans;
+
   const struct model * model = &haunted_mansion_collision_model;
   const struct object * object = &haunted_mansion_collision_house_coll_display;
 
-  float tx = screen[0][3];
-  float ty = screen[2][3];
-
   for (int i = 0; i < object->line_count; i++) {
 
     const union line * line = &object->line[i];
 
-    vec3 la = model->position[line->a];
-    vec3 lb = model->position[line->b];
+    vec3 b1 = trans * model->position[line->a];
+    vec3 b2 = trans * model->position[line->b];
 
-    vec2 b1 = {la.x + tx, la.z + ty};
-    vec2 b2 = {lb.x + tx, lb.z + ty};
-
-    vec2 tu = line_intersection({a1.x, a1.y},
-                                {a2.x, a2.y},
-                                {b1.x, b1.y},
-                                {b2.x, b2.y});
+    vec2 tu = line_intersection({a1.x, a1.z},
+                                {a2.x, a2.z},
+                                {b1.x, b1.z},
+                                {b2.x, b2.z});
 
     if (tu.x >= 0.0f && tu.x <= 1.0f && tu.y >= 0.0f && tu.y <= 1.0f) {
       collided[i] = true;
@@ -835,7 +831,7 @@ void render_collision(ta_parameter_writer& writer, const mat4x4& model_trans, co
                 collided[i] ? 0xffff0000 : base_color);
   }
 
-  vec3 a = {last_dx * -2, last_dy * -2, 1};
+  vec3 a = {last_dx * -2, last_dy * 2, 1};
   vec3 b = {0, 0, 1};
   if (a.z > 0) {
     render_line(writer,
@@ -999,8 +995,8 @@ constexpr inline mat4x4 update_analog(const mat4x4& model_trans, const mat4x4& s
   last_dx = x;
   last_dy = y;
 
-  vec3 a = {last_dx * -2, last_dy * -2, 1.f};
-  vec3 b = {0, 0, 1.f};
+  vec3 a = {last_dx * -2, 0.f, last_dy * 2};
+  vec3 b = {0, 0.f, 1.f};
 
   if (line_has_collision(a, b, model_trans, screen)) {
     x = 0;