From 565273d4890abc6d2da12449a378ee4b9855e143 Mon Sep 17 00:00:00 2001
From: Emily <louis_d@live.com>
Date: Mon, 16 Oct 2023 18:44:51 -0400
Subject: [PATCH] Fix Raycast and implement tests

---
 Common/World/Raycast.cs      | 14 +++++++-------
 Test/Tests/BlockViewSuite.cs | 17 ++++++++++++++++-
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/Common/World/Raycast.cs b/Common/World/Raycast.cs
index 7eba0bd..8841fcd 100644
--- a/Common/World/Raycast.cs
+++ b/Common/World/Raycast.cs
@@ -53,28 +53,28 @@ public static class Raycast {
                 // Gets the one integer intersection coordinate
                 // axis * blockPos isolates one coordinate from blockPos
                 // adding (-1, -1, -1) * the min of axis and (0, 0, 0) offsets the integer coordinate if the vector is intersecting from the other side
-                var worldPos = axis * blockPos + -ivec3.Ones * ivec3.Min(axis, ivec3.Zero);
+                dvec3 worldPos = ivec3.Abs(axis) * blockPos + -ivec3.Ones * ivec3.Min(axis, ivec3.Zero);
                 var direction = delta.Normalized;
                 
                 // intersect with a yz plane
                 if (axis.x != 0) {
                     double time = (start.x - worldPos.x) / direction.x;
-                    worldPos.y = (int)(direction.y * time);
-                    worldPos.z = (int)(direction.z * time);
+                    worldPos.y = start.y + direction.y * time;
+                    worldPos.z = start.z + direction.z * time;
                     return new(blockPos, worldPos, axis);
                 }
                 // intersect with an xz plane
                 if (axis.y != 0) {
                     double time = (start.y - worldPos.y) / direction.y;
-                    worldPos.x = (int)(direction.x * time);
-                    worldPos.z = (int)(direction.z * time);
+                    worldPos.x = start.x + direction.x * time;
+                    worldPos.z = start.z + direction.z * time;
                     return new(blockPos, worldPos, axis);
                 }
                 // intersect with a xy plane
                 if (axis.z != 0) {
                     double time = (start.z - worldPos.z) / direction.z;
-                    worldPos.x = (int)(direction.x * time);
-                    worldPos.y = (int)(direction.y * time);
+                    worldPos.x = start.x + direction.x * time;
+                    worldPos.y = start.y + direction.y * time;
                     return new(blockPos, worldPos, axis);
                 }
             }
diff --git a/Test/Tests/BlockViewSuite.cs b/Test/Tests/BlockViewSuite.cs
index b8f1e82..06f7cbc 100644
--- a/Test/Tests/BlockViewSuite.cs
+++ b/Test/Tests/BlockViewSuite.cs
@@ -1,6 +1,8 @@
 using System;
 using System.Collections.Generic;
+using GlmSharp;
 using Voxel.Common.Tile;
+using Voxel.Common.Util;
 using Voxel.Common.World;
 using Voxel.Test.Mocks;
 
@@ -11,9 +13,22 @@ public class BlockViewSuite : TestSuite {
     protected override Dictionary<string, Test> DefineTests()
         => new() {
             ["Raycast"] = () => {
+                // Mock block view with all tiles below 0 solid
                 var mock = new BlockViewMock(pos => pos.y < 0 ? Blocks.Stone : Blocks.Air);
 
-                Console.WriteLine(mock.Cast(new(0.5, 10.2, 0.8), new(5.333, -9.4, -5.1674)));
+                var rng = new Random(0);
+                double RandomCoord()
+                    => rng.NextDouble() * 200d - 100d;
+                
+                // Test downward casts
+                for (int i = 0; i < 100; i++) {
+                    // world pos on the top surface of the tested block
+                    var randomPos = new dvec3(RandomCoord(), 0, RandomCoord());
+                    
+                    var hit = mock.Cast(randomPos + dvec3.UnitY, randomPos - dvec3.UnitY);
+                    Assert(hit?.BlockPos == randomPos.WorldToBlockPosition() - ivec3.UnitY, "Hit correct block");
+                    Assert((hit?.WorldPos - randomPos)?.Length < 0.0001f, $"Hit correct world position");
+                }
             }
         };
 }