From c508f08ce4841eabbcaf5df7c31ff4331aa9750c Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sat, 8 Jan 2022 13:39:36 +0000
Subject: Tweak ray tracer calls to account for scale

---
 game/geoData.cpp  | 18 ++++++++----------
 game/geoData.h    |  4 ++--
 test/test-geo.cpp | 33 +++++++++++++++------------------
 3 files changed, 25 insertions(+), 30 deletions(-)

diff --git a/game/geoData.cpp b/game/geoData.cpp
index 4537026..32ec55e 100644
--- a/game/geoData.cpp
+++ b/game/geoData.cpp
@@ -95,30 +95,28 @@ GeoData::positionAt(const glm::vec2 wcoord) const
 	return wcoord || heightMid;
 }
 
-GeoData::RayTracer::RayTracer(glm::vec2 p0, glm::vec2 p1, float scale) : p {glm::floor(p0)}, d {glm::abs(p1 - p0)}
+GeoData::RayTracer::RayTracer(glm::vec2 p0, glm::vec2 p1) : p {glm::floor(p0)}, d {glm::abs(p1)}
 {
 	using Limits = std::numeric_limits<typename glm::vec2::value_type>;
 	static_assert(Limits::has_infinity);
-	static constexpr const glm::vec2 inf {Limits::infinity(), -Limits::infinity()};
 
-	auto byAxis = [this, p0, p1, scale](auto axis) {
+	auto byAxis = [this, p0, p1](auto axis) {
 		if (d[axis] == 0) {
 			inc[axis] = 0;
-			return inf[axis];
+			return Limits::infinity();
 		}
-		else if (p1[axis] > p0[axis]) {
-			inc[axis] = scale;
-			return (std::floor(p0[axis]) + 1 - p0[axis]) * d[1 - axis];
+		else if (p1[axis] > 0) {
+			inc[axis] = 1;
+			return (std::floor(p0[axis]) + 1.F - p0[axis]) * d[1 - axis];
 		}
 		else {
-			inc[axis] = -scale;
+			inc[axis] = -1;
 			return (p0[axis] - std::floor(p0[axis])) * d[1 - axis];
 		}
 	};
 
 	error = byAxis(0);
 	error -= byAxis(1);
-	inc.z = scale;
 }
 
 glm::vec2
@@ -129,7 +127,7 @@ GeoData::RayTracer::next()
 	static constexpr const glm::vec2 m {1, -1};
 	const int axis = (error > 0) ? 1 : 0;
 	p[axis] += inc[axis];
-	error += d[1 - axis] * m[axis] * inc.z;
+	error += d[1 - axis] * m[axis];
 
 	return cur;
 }
diff --git a/game/geoData.h b/game/geoData.h
index 7bd6ae5..a296205 100644
--- a/game/geoData.h
+++ b/game/geoData.h
@@ -34,7 +34,7 @@ public:
 
 	class RayTracer {
 	public:
-		RayTracer(glm::vec2 p0, glm::vec2 p1, float scale);
+		RayTracer(glm::vec2 p0, glm::vec2 p1);
 
 		glm::vec2 next();
 
@@ -42,7 +42,7 @@ public:
 		glm::vec2 p;
 		const glm::vec2 d;
 		float error;
-		glm::vec3 inc;
+		glm::vec2 inc;
 	};
 
 protected:
diff --git a/test/test-geo.cpp b/test/test-geo.cpp
index f0ed693..07e3bd1 100644
--- a/test/test-geo.cpp
+++ b/test/test-geo.cpp
@@ -97,14 +97,11 @@ BOOST_AUTO_TEST_CASE(get_height_at)
 	BOOST_CHECK_EQUAL(positionAt({2.5F, 2.5F}), glm::vec3(2.5F, 2.5F, 2.5F));
 }
 
-using TestRayTracerData = std::tuple<glm::vec2, glm::vec2, float, std::vector<glm::vec2>>;
+using TestRayTracerData = std::tuple<glm::vec2, glm::vec2, glm::vec2::value_type, std::vector<glm::vec2>>;
+BOOST_TEST_DECORATOR(*boost::unit_test::timeout(1))
 BOOST_DATA_TEST_CASE(raytracer,
 		boost::unit_test::data::make<TestRayTracerData>({
-				{{0, 0}, {0, 0}, 3,
-						{
-								{0, 0},
-						}},
-				{{0, 0}, {4, 5}, 4,
+				{{1, 2}, {4, 5}, 4,
 						{
 								{0, 0},
 								{0, 4},
@@ -114,26 +111,26 @@ BOOST_DATA_TEST_CASE(raytracer,
 								{8, 12},
 								{12, 12},
 								{12, 16},
-								{16, 16},
+								{12, 20},
 								{16, 20},
 						}},
 				{{-1, -1}, {-4, -5}, 5,
 						{
-								{-1, -1},
-								{-6, -1},
-								{-6, -6},
-								{-6, -11},
-								{-11, -11},
-								{-11, -16},
-								{-16, -16},
-								{-16, -21},
+								{-5, -5},
+								{-5, -10},
+								{-10, -10},
+								{-10, -15},
+								{-15, -15},
+								{-15, -20},
+								{-20, -20},
+								{-20, -25},
 						}},
 		}),
-		start, end, scale, points)
+		start, dir, scale, points)
 {
-	GeoData::RayTracer rt {start, end, scale};
+	GeoData::RayTracer rt {start / scale, glm::normalize(dir)};
 	for (const auto & point : points) {
-		BOOST_CHECK_CLOSE_VEC(point, rt.next());
+		BOOST_CHECK_CLOSE_VEC(point, rt.next() * scale);
 	}
 }
 
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