From eee63a7350e7e83bba985bb8a435f97f35b5879d Mon Sep 17 00:00:00 2001
From: Fabien Freling <public@ffreling.com>
Date: Mon, 6 Apr 2020 23:35:51 +0200
Subject: [PATCH] assert on negative distance

---
 src/engine.rs | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/src/engine.rs b/src/engine.rs
index 77e2732..0232553 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -31,9 +31,14 @@ struct Player {
 impl Player {
     pub fn player_space_distance(&self, other: Position) ->f64 {
         let rad = self.angle.to_radians();
-        let x = (other.x - self.pos.x) * rad.cos();
-        let y = (other.y - self.pos.y) * rad.sin();
-        x + y
+        let dx = other.x - self.pos.x;
+        let dy = other.y - self.pos.y;
+        let x = dx * rad.cos();
+        let y = dy * rad.sin();
+        let distance = x + y;
+        println!("angle: {}, dx: {}, dy: {}, x; {}, y: {}", self.angle, dx, dy, x, y);
+        assert!(distance.is_sign_positive());
+        distance
     }
 }
 
@@ -73,8 +78,8 @@ fn step_for_angle(angle: Radian) -> (f64, f64) {
     match angle {
         x if x == 0.0 => (0.0, std::f64::INFINITY),
         x if x == PI * 0.5 => (std::f64::INFINITY, 0.0),
-        x if x == PI => (0.0, std::f64::NEG_INFINITY),
-        x if x == PI * 1.5 => (std::f64::NEG_INFINITY, 0.0),
+        x if x == PI => (0.0, std::f64::INFINITY),
+        x if x == PI * 1.5 => (std::f64::INFINITY, 0.0),
         x if (0.0..(PI * 0.5)).contains(&x) => (angle.tan(), ((PI * 0.5) - angle).tan()),
         x if ((PI * 0.5)..PI).contains(&x) => (-x.tan(), -((x - (PI * 0.5)).tan())),
         x if (PI..(PI * 1.5)).contains(&x) => (-x.tan(), -(((PI * 1.5) - x).tan())),
@@ -197,7 +202,6 @@ impl Engine {
             let ray_radian = ray_angle.to_radians();
             let (tile, pos) = closest_point(&self.level, &self.player.pos, ray_radian);
             let distance = self.player.player_space_distance(pos);
-            //assert!(distance.is_sign_positive());
             if tile == Tile::Wall {
                 let wall_height = (self.h / (distance * 3.0)).min(self.h);
                 let wall_color = match pos {
@@ -280,6 +284,9 @@ mod tests {
         fcmp(player.player_space_distance(super::Position { x: 2., y: 4. }), 2.);
         fcmp(player.player_space_distance(super::Position { x: 3., y: 4. }), 2.);
 
+        player.angle = 135.;
+        fcmp(player.player_space_distance(super::Position { x: 0., y: 2. }), 2.);
+
         player.angle = 180.;
         fcmp(player.player_space_distance(super::Position { x: 0., y: 1. }), 2.);
         fcmp(player.player_space_distance(super::Position { x: 0., y: 2. }), 2.);
@@ -317,6 +324,7 @@ mod tests {
             fcmp(step_x, x);
         };
 
+        step_cmp(30.0, 0.5773502691896257, 1.7320508075688776);
         step_cmp(45.0, 1.0, 1.0);
         step_cmp(90.0 + 45.0, 1.0, -1.0);
         step_cmp(180.0 + 45.0, -1.0, -1.0);
@@ -362,11 +370,11 @@ mod tests {
         for n in 0..20 {
             let left_ray_angle = (((n as f64) * step) + 360.0) % 360.0;
             let left_ray_radian = left_ray_angle.to_radians();
-            let (left_tile, left_pos) = super::closest_point(&level, &position, left_ray_radian);
+            let (_left_tile, left_pos) = super::closest_point(&level, &position, left_ray_radian);
 
             let right_ray_angle = ((-(n as f64) * step) + 360.0) % 360.0;
             let right_ray_radian = right_ray_angle.to_radians();
-            let (right_tile, right_pos) = super::closest_point(&level, &position, right_ray_radian);
+            let (_right_tile, right_pos) = super::closest_point(&level, &position, right_ray_radian);
 
             println!("left: {:?}, angle: {}", left_pos, left_ray_angle);
             println!("right: {:?}, angle: {}", right_pos, right_ray_angle);