From 95387c4f2f656b86ec81bd01ea9473b41baea76a Mon Sep 17 00:00:00 2001
From: quou <quou@disroot.org>
Date: Sun, 28 Jul 2024 13:52:20 +1000
Subject: Textured walls and vastly increase the speed of the raycaster.

---
 render.c | 85 +++++++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 52 insertions(+), 33 deletions(-)

diff --git a/render.c b/render.c
index 86e61f7..7c4dd77 100644
--- a/render.c
+++ b/render.c
@@ -714,6 +714,9 @@ void ren_mesh(
 	}
 }
 
+/* temp */
+#include "asset.h"
+
 void ren_map(
 	Renderer* r,
 	const struct Map* map,
@@ -723,54 +726,70 @@ void ren_map(
 ) {
 	int x, w, h, hh;
 	const int* data = (const int*)&map[1];
+	/* temp */
+	const Texture* texture = get_texture(asset_id_gun_texture);
 	w = r->vp[0] << fbits;
 	h = r->vp[1] << fbits;
 	hh = h / 2;
 	for (x = r->clip[0]; x < r->clip[2]; x++) {
-		Line l;
 		int ray = ((2 * x) << (fbits * 2)) / w - f1;
-		int d[2], plane[2];
-		d[0] = ((left[0] * ray) >> fbits);
-		d[1] = ((left[1] * ray) >> fbits);
-		plane[0] = pos[0] - d[0];
-		plane[1] = pos[1] - d[1];
-		d[0] = dir[0] - d[0];
-		d[1] = dir[1] - d[1];
-		d[0] = (pos[0] + d[0] * 4);
-		d[1] = (pos[1] + d[1] * 4);
-		init_line(&l, pos, d);
+		int d[2];
+		int delta[2], step[2], dside[2];
+		int mp[2];
+		d[0] = dir[0] - ((left[0] * ray) >> fbits);
+		d[1] = dir[1] - ((left[1] * ray) >> fbits);
+		mp[0] = pos[0] >> fbits;
+		mp[1] = pos[1] >> fbits;
+		delta[0] = !d[0]? f1*30: abs((f1 << fbits) / d[0]);
+		delta[1] = !d[1]? f1*30: abs((f1 << fbits) / d[1]);
+		if (d[0] < 0) {
+			step[0] = -1;
+			dside[0] = ((pos[0] - (mp[0] << fbits)) * delta[0]) >> fbits;
+		} else {
+			step[0] = 1;
+			dside[0] = (((mp[0] << fbits) + f1 - pos[0]) * delta[0]) >> fbits;
+		}
+		if (d[1] < 0) {
+			step[1] = -1;
+			dside[1] = ((pos[1] - (mp[1] << fbits)) * delta[1]) >> fbits;
+		} else {
+			step[1] = 1;
+			dside[1] = (((mp[1] << fbits) + f1 - pos[1]) * delta[1]) >> fbits;
+		}
 		while (1) {
-			int mp[2], tile;
-			mp[0] = l.x >> fbits;
-			mp[1] = l.y >> fbits;
-			if (
-				mp[0] < 0 ||
-				mp[1] < 0 ||
-				mp[0] >= map->w ||
-				mp[1] >= map->h
-			) break;
-			tile = data[mp[0] + mp[1] * map->w];
-			if (tile) {
-				int lp[2], sy, ey, d, y;
-				lp[0] = l.x;
-				lp[1] = l.y;
-				d = vec_dist(lp, lp, plane, 2);
-				sy = (r->vp[1] / 2) - (((hh << fbits) / d) >> fbits);
-				ey = (r->vp[1] / 2) + (((hh << fbits) / d) >> fbits);
+			int dist, u;
+			if (dside[0] < dside[1]) {
+				dside[0] += delta[0];
+				mp[0] += step[0];
+				dist = dside[0] - delta[0];
+				u = pos[1] + ((dist * d[1]) >> fbits);
+			} else {
+				dside[1] += delta[1];
+				mp[1] += step[1];
+				dist = dside[1] - delta[1];
+				u = pos[0] + ((dist * d[0]) >> fbits);
+			}
+			if (mp[0] < 0) break;
+			if (mp[1] < 0) break;
+			if (mp[0] >= map->w) break;
+			if (mp[1] >= map->h) break;
+			if (data[mp[0] + mp[1] * map->w]) {
+				int y;
+				int sy = (r->vp[1] / 2) - (((hh << fbits) / dist) >> fbits);
+				int ey = (r->vp[1] / 2) + (((hh << fbits) / dist) >> fbits);
 				sy = maxi(sy, r->clip[1]);
 				ey = mini(ey, r->clip[3]);
 				for (y = sy; y < ey; y++) {
 					int coord = x + y * r->vp[0];
-					Colour c = { 0, 0, 0, 255 };
-					c.r = (((16 << fbits ) - d) / 16);
-					if (d < r->d[coord]) {
-						r->d[coord] = d;
+					if (dist < r->d[coord]) {
+						int v = ((y - sy) << fbits) / (ey - sy);
+						Colour c = sample_tex(texture, u, v);
+						r->d[coord] = dist;
 						r->t[coord] = c;
 					}
 				}
 				break;
 			}
-			step_line(&l);
 		}
 	}
 }
-- 
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