From a5b20dcd57ddf7bdac8d9bce1aabf934badd837d Mon Sep 17 00:00:00 2001
From: Paweł Redman <pawel.redman@gmail.com>
Date: Thu, 12 Apr 2018 14:00:53 +0200
Subject: Ray tracing against cmodels (WIP).

---
 src/world.cpp | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 70 insertions(+), 6 deletions(-)

(limited to 'src/world.cpp')

diff --git a/src/world.cpp b/src/world.cpp
index 640ac6e..b03105e 100644
--- a/src/world.cpp
+++ b/src/world.cpp
@@ -319,6 +319,76 @@ static inline size_t quadrant(v2f_t dx)
 	}
 }
 
+trace_t ray_v_rect(v2f_t start, v2f_t end, rectf_t rect)
+{
+	v2f_t dx, tdelta, dims;
+	size_t quad;
+	trace_t res;
+
+	if (rect.contains(start)) {
+		res.hit = true;
+		res.end = start;
+		res.frac = 0.0f;
+		return res;
+	}
+
+	dx = end - start;
+
+	quad = quadrant(dx);
+	if (quad == 4)
+		goto out_no_hit;
+
+	// If necessary, transform (with simple X/Y reflections) the coordinate
+	// system, so that dx lies in the first quadrant.
+
+	start ^= transforms[quad];
+	dx ^= transforms[quad];
+	end ^= transforms[quad];
+
+	dims = rect.dims();
+	rect.v[0] ^= transforms[quad];
+	rect.v[1] ^= transforms[quad];
+
+	// Find the closest point on the rectangle and transform the coordinates
+	// so that it lies at (0, 0).
+
+	tdelta[0] = std::min(rect.v[0][0], rect.v[1][0]);
+	tdelta[1] = std::min(rect.v[0][1], rect.v[1][1]);
+	start -= tdelta;
+
+	// Project onto x = 0.
+	res.frac = -start[0] / dx[0];
+	if (res.frac >= 0.0f && res.frac <= 1.0f) {
+		float y;
+
+		y = start[1] + res.frac * dx[1];
+		if (y >= 0 && y <= dims[1]) {
+			res.hit = true;
+			res.end = (v2f_t(0, y) + tdelta) ^ transforms[quad];
+			return res;
+		}
+	}
+
+	// Project onto y = 0.
+	res.frac = -start[1] / dx[1];
+	if (res.frac >= 0.0f && res.frac <= 1.0f) {
+		float x;
+
+		x = start[0] + res.frac * dx[0];
+		if (x >= 0 && x <= dims[0]) {
+			res.hit = true;
+			res.end = (v2f_t(x, 0) + tdelta) ^ transforms[quad];
+			return res;
+		}
+	}
+
+out_no_hit:
+	res.hit = false;
+	res.end = end ^ transforms[quad];
+	res.frac = 1.0f;
+	return res;
+}
+
 trace_t world_t::trace(v2f_t start, v2f_t end, cflags_t cflags)
 {
 	v2f_t x, dx;
@@ -382,12 +452,6 @@ trace_t world_t::trace(v2f_t start, v2f_t end, cflags_t cflags)
 	}
 }
 
-trace_t trace_cmodel(v2f_t start, v2f_t end, const cmodel_t *cmodel)
-{
-	// TODO
-	return {0};
-}
-
 entity_t::entity_t(int type_)
 {
 	type = type_;
-- 
cgit