Minor tweak

1 files changed, 37 insertions, 33 deletions

diff --git a/src/render.zig b/src/render.zig
index 8d2faca..e2aa401 100644
--- a/src/render.zig
+++ b/src/render.zig
@@ -70,8 +70,8 @@ fn fasterColourBlend(onto: Colour, from: Colour) Colour {
 }
 
 const LocalCoordHit = struct {
-    local_dist : f32,
-    frac : f32,
+    local_dist: f32,
+    frac: f32,
 };
 
 // The primary observation is: if a line segment AB disconnects the unit square,
@@ -81,16 +81,18 @@ const LocalCoordHit = struct {
 
 // TODO: handle hitting vertices
 fn hitDistLocalCoords(
-    ray0: [2]f32,
-    ray1: [2]f32,
+    ray0_x: f32,
+    ray0_y: f32,
+    ray1_x: f32,
+    ray1_y: f32,
     vertices: []const [2]f32,
 ) ?LocalCoordHit {
-    const rdy = ray1[1] - ray0[1];
-    const rdx = ray1[0] - ray0[0];
+    const rdy = ray1_y - ray0_y;
+    const rdx = ray1_x - ray0_x;
     const rdist = std.math.sqrt(rdx * rdx + rdy * rdy);
 
     var vp = vertices[0];
-    var crossp: f32 = rdy * (vp[0] - ray0[0]) - rdx * (vp[1] - ray0[1]);
+    var crossp: f32 = rdy * (vp[0] - ray0_x) - rdx * (vp[1] - ray0_y);
 
     // if (crossp == 0) {
     //     // hit a vertex exactly
@@ -100,7 +102,7 @@ fn hitDistLocalCoords(
     // }
 
     var ret_val: ?LocalCoordHit = null;
-    var v : [2]f32 = undefined;
+    var v: [2]f32 = undefined;
     var cross: f32 = 0;
     var i: usize = 1;
     while (i < vertices.len) : ({
@@ -109,7 +111,7 @@ fn hitDistLocalCoords(
         i += 1;
     }) {
         v = vertices[i];
-        cross = rdy * (v[0] - ray0[0]) - rdx * (v[1] - ray0[1]);
+        cross = rdy * (v[0] - ray0_x) - rdx * (v[1] - ray0_y);
         // if (cross == 0) {
         //     const dx = v[0] - ray0[0];
         //     const dy = v[1] - ray0[1];
@@ -120,7 +122,7 @@ fn hitDistLocalCoords(
         //         return_val = new_distance;
         //     }
         // } else
-            {
+        {
             if (crossp * cross < 0) {
                 const vdx = v[0] - vp[0];
                 const vdy = v[1] - vp[1];
@@ -129,12 +131,12 @@ fn hitDistLocalCoords(
                 // so along ray0->ray1 which we use for fast distance, and frac
                 // indexes it along vp->v which we use for texture mapping.
                 const denom = (rdx * vdy - vdx * rdy);
-                const t = (vdx * (ray0[1] - vp[1]) - vdy * (ray0[0] - vp[0])) / denom;
+                const t = (vdx * (ray0_y - vp[1]) - vdy * (ray0_x - vp[0])) / denom;
                 const frac = crossp / denom;
                 const new_distance = rdist * t;
 
                 if (ret_val == null or (new_distance < ret_val.?.local_dist)) {
-                    ret_val = LocalCoordHit{.local_dist = new_distance, .frac = frac};
+                    ret_val = LocalCoordHit{ .local_dist = new_distance, .frac = frac };
                 }
             }
         }
@@ -403,29 +405,31 @@ pub fn Renderer(PlaneWidth: f32, PlaneHeight: f32) type {
 
                     // Are we drawing vertical surfaces?
                     if (cell.floor_height > 0 or cell.draw_down) {
-                        const ray0: [2]f32 = if (hit_horizontal)
-                            [2]f32{
-                                std.math.modf(distance * cosra + ppos_x).fpart,
-                                (if (step_y > 0) 0 else 1),
-                            }
-                        else
-                            [2]f32{
-                                (if (step_x > 0) 0 else 1),
-                                std.math.modf(distance * sinra + ppos_y).fpart,
-                            };
+                        var ray0_x: f32 = undefined;
+                        var ray0_y: f32 = undefined;
+                        var ray1_x: f32 = undefined;
+                        var ray1_y: f32 = undefined;
 
-                        const ray1: [2]f32 = if (next_hit_horizontal)
-                            [2]f32{
-                                std.math.modf(next_distance * cosra + ppos_x).fpart,
-                                (if (step_y > 0) 1 else 0),
-                            }
-                        else
-                            [2]f32{
-                                (if (step_x > 0) 1 else 0),
-                                std.math.modf(next_distance * sinra + ppos_y).fpart,
-                            };
+                        const ray_enter_y: f32 = if (step_y > 0) 0 else 1;
+                        const ray_enter_x: f32 = if (step_x > 0) 0 else 1;
+
+                        if (hit_horizontal) {
+                            ray0_x = std.math.modf(distance * cosra + ppos_x).fpart;
+                            ray0_y = ray_enter_y;
+                        } else {
+                            ray0_x = ray_enter_x;
+                            ray0_y = std.math.modf(distance * sinra + ppos_y).fpart;
+                        }
+
+                        if (next_hit_horizontal) {
+                            ray1_x = std.math.modf(next_distance * cosra + ppos_x).fpart;
+                            ray1_y = 1 - ray_enter_y;
+                        } else {
+                            ray1_x = 1 - ray_enter_x;
+                            ray1_y = std.math.modf(next_distance * sinra + ppos_y).fpart;
+                        }
 
-                        if (hitDistLocalCoords(ray0, ray1, cell.vertices)) |dist_frac| {
+                        if (hitDistLocalCoords(ray0_x, ray0_y, ray1_x, ray1_y, cell.vertices)) |dist_frac| {
                             // TODO: Correct for fisheye?
                             const adj_distance = distance + dist_frac.local_dist;