From b8a4d4fe37827a2d2a9f3ab8c94cc61dc11e2640 Mon Sep 17 00:00:00 2001
From: Allanis <allanis@saracraft.net>
Date: Fri, 20 Sep 2013 23:11:38 +0100
Subject: [PATCH] [Fix] LineSprite is almost working flawlessly.

---
 src/collision.c | 77 +++++++++++++++++++++++++++++++++++++------------
 1 file changed, 59 insertions(+), 18 deletions(-)

diff --git a/src/collision.c b/src/collision.c
index 0eb65c0..102e124 100644
--- a/src/collision.c
+++ b/src/collision.c
@@ -145,7 +145,8 @@ int CollideLineSprite(const Vec2* ap, double ad, double al,
   (void) bsx;
   (void) bsy;
 
-  double ep[2], tr[2], v[2], mod;
+  int x, y, rbsy, bbx, bby;
+  double ep[2], bl[2], tr[2], v[2], mod;
   int hits;
   Vec2 tmp_crash, border[2];
 
@@ -154,22 +155,26 @@ int CollideLineSprite(const Vec2* ap, double ad, double al,
   ep[1] = ap->y + al*sin(ad);
 
   /* Set up top right corner of the rectangle. */
-  tr[0] = ap->x + al*cos(ad);
-  tr[1] = ap->y + al*sin(ad);
+  tr[0] = bp->x + bt->sw/2.;
+  tr[1] = bp->y + bt->sh/2.;
+
+  /* Set up bottom left corner of the rectangle. */
+  bl[0] = bp->x - bt->sw/2.;
+  bl[1] = bp->y - bt->sh/2.;
 
   /* Start check for rectangular collision. */
   hits = 0;
 
   /* Left border. */
   if(CollideLineLine(ap->x, ap->y, ep[0], ep[1],
-        bp->x, bp->y, bp->x, tr[1], &tmp_crash) != 0) {
+        bl[0], bl[1], bl[0], tr[1], &tmp_crash) != 0) {
     border[hits].x = tmp_crash.x;
     border[hits].y = tmp_crash.y;
     hits++;
   }
   /* Top border. */
   if(CollideLineLine(ap->x, ap->y, ep[0], ep[1],
-        bp->x, tr[1], tr[0], tr[1], &tmp_crash) != 0) {
+        bl[0], tr[1], tr[0], tr[1], &tmp_crash) != 0) {
     border[hits].x = tmp_crash.x;
     border[hits].y = tmp_crash.y;
     hits++;
@@ -177,14 +182,14 @@ int CollideLineSprite(const Vec2* ap, double ad, double al,
   /* Now we are going to have to make sure hits isn't 2. */
   /* Right border. */
   if((hits < 2) && CollideLineLine(ap->x, ap->y, ep[0], ep[1],
-        tr[0], tr[1], tr[0], bp->y, &tmp_crash) != 0) {
+        tr[0], tr[1], tr[0], bl[1], &tmp_crash) != 0) {
     border[hits].x = tmp_crash.x;
     border[hits].y = tmp_crash.y;
     hits++;
   }
   /* Bottom border. */
   if((hits < 2) && CollideLineLine(ap->x, ap->y, ep[0], ep[1],
-        tr[0], bp->y, bp->x, bp->y, &tmp_crash) != 0) {
+        tr[0], bl[1], bl[0], bl[1], &tmp_crash) != 0) {
     border[hits].x = tmp_crash.x;
     border[hits].y = tmp_crash.y;
     hits++;
@@ -204,24 +209,60 @@ int CollideLineSprite(const Vec2* ap, double ad, double al,
     return 1;
   }
 
-  crash[0].x = border[0].x;
-  crash[0].y = border[0].y;
-  crash[1].x = border[1].x;
-  crash[1].y = border[1].y;
-  return 1;
-
-  /* @todo Now we do a pixel perfect approach. */
-
+  /* Now we do a pixel perfect approach. */
+  hits = 0;
   /* directional vector (normalised). */
   v[0] = border[1].x - border[0].x;
   v[1] = border[1].y - border[0].y;
   /* Normalize. */
-  mod = 2*MOD(v[0], v[1]); /* Multiply by two to reduce check amount. */
+  mod = MOD(v[0], v[1])/2.; /* Multiply by two to reduce check amount. */
   v[0] /= mod;
   v[1] /= mod;
 
+  /* Real vertical sprite value (flipped). */
+  rbsy = bt->sy - bsy - 1;
+  /* Set up the base points. */
+  bbx =  bsx*(int)(bt->sw);
+  bby = rbsy*(int)(bt->sh);
+
+
   /* We start checking first border until we find collision. */
-  tmp_crash.x = border[0].x;
-  tmp_crash.y = border[0].y;
+  x = border[0].x - bl[0] + v[0];
+  y = border[0].y - bl[1] + v[1];
+  while((x > 0.) && (x < bt->sw) && (y > 0.) && (y < bt->sh)) {
+    /* Is non-transparent. */
+    if(!gl_isTrans(bt, bbx+(int)x, bby+(int)y)) {
+      crash[0].x = x + bl[0];
+      crash[0].y = y + bl[1];
+      hits++;
+      break;
+    }
+
+    x += v[0];
+    y += v[1];
+  }
+
+  if(hits != 1) return 0; /* We actually missed. */
+
+  /* Now we check the second border. */
+  x = border[1].x - bl[0] - v[0];
+  y = border[1].y - bl[1] - v[1];
+  while((x > 0.) && (x < bt->sw) && (y > 0.) && (y < bt->sh)) {
+    /* Is non-transparent. */
+    if(!gl_isTrans(bt, bbx+(int)x, bby+(int)y)) {
+      crash[1].x = x + bl[0];
+      crash[1].y = y + bl[1];
+      hits++;
+      break;
+    }
+
+    x -= v[0];
+    y -= v[1];  
+  }
+
+  if(hits != 2) return 0; /* We actually missed. */
+
+  /* We hit! */
+  return 1;
 }