From 60dc01dc258db842e229351b871d0989e3e7d62c Mon Sep 17 00:00:00 2001
From: gregorycu <gregory.currie@gmail.com>
Date: Tue, 27 Jan 2015 23:33:54 +1100
Subject: [PATCH] Fix jumping at node edge

---
 src/collision.cpp | 66 ++++++++++++-----------------------------------
 1 file changed, 17 insertions(+), 49 deletions(-)

diff --git a/src/collision.cpp b/src/collision.cpp
index 2ae59b38f..a2d17d51a 100644
--- a/src/collision.cpp
+++ b/src/collision.cpp
@@ -248,8 +248,9 @@ collisionMoveResult collisionMoveSimple(Environment *env, IGameDef *gamedef,
 
 	bool any_position_valid = false;
 
+	// The order is important here, must be y first
+	for(s16 y = max_y; y >= min_y; y--)
 	for(s16 x = min_x; x <= max_x; x++)
-	for(s16 y = min_y; y <= max_y; y++)
 	for(s16 z = min_z; z <= max_z; z++)
 	{
 		v3s16 p(x,y,z);
@@ -404,15 +405,17 @@ collisionMoveResult collisionMoveSimple(Environment *env, IGameDef *gamedef,
 			Go through every nodebox, find nearest collision
 		*/
 		for (u32 boxindex = 0; boxindex < cboxes.size(); boxindex++) {
-			// Ignore if already stepped up this nodebox.
-			if(is_step_up[boxindex])
-				continue;
-
 			// Find nearest collision of the two boxes (raytracing-like)
 			f32 dtime_tmp;
 			int collided = axisAlignedCollision(
 					cboxes[boxindex], movingbox, *speed_f, d, &dtime_tmp);
 
+			// Ignore if already stepped up this nodebox.
+			if (is_step_up[boxindex]) {
+				pos_f->Y += (cboxes[boxindex].MaxEdge.Y - movingbox.MinEdge.Y);
+				continue;
+			}
+
 			if (collided == -1 || dtime_tmp >= nearest_dtime)
 				continue;
 
@@ -462,10 +465,12 @@ collisionMoveResult collisionMoveSimple(Environment *env, IGameDef *gamedef,
 				is_collision = false;
 
 			CollisionInfo info;
-			if (is_object[nearest_boxindex])
+			if (is_object[nearest_boxindex]) {
 				info.type = COLLISION_OBJECT;
-			else
+				result.standing_on_object = true;
+			} else {
 				info.type = COLLISION_NODE;
+			}
 
 			info.node_p = node_positions[nearest_boxindex];
 			info.bouncy = bouncy;
@@ -483,12 +488,13 @@ collisionMoveResult collisionMoveSimple(Environment *env, IGameDef *gamedef,
 					speed_f->X = 0;
 				result.collides = true;
 				result.collides_xz = true;
-			}
-			else if(nearest_collided == 1) { // Y
-				if (fabs(speed_f->Y) > BS * 3)
+			} else if(nearest_collided == 1) { // Y
+				if (fabs(speed_f->Y) > BS * 3) {
 					speed_f->Y *= bounce;
-				else
+				} else {
 					speed_f->Y = 0;
+					result.touching_ground = true;
+				}
 				result.collides = true;
 			} else if(nearest_collided == 2) { // Z
 				if (fabs(speed_f->Z) > BS * 3)
@@ -509,43 +515,5 @@ collisionMoveResult collisionMoveSimple(Environment *env, IGameDef *gamedef,
 		}
 	}
 
-	/*
-		Final touches: Check if standing on ground, step up stairs.
-	*/
-	aabb3f box = box_0;
-	box.MinEdge += *pos_f;
-	box.MaxEdge += *pos_f;
-	for (u32 boxindex = 0; boxindex < cboxes.size(); boxindex++) {
-		const aabb3f& cbox = cboxes[boxindex];
-
-		/*
-			See if the object is touching ground.
-
-			Object touches ground if object's minimum Y is near node's
-			maximum Y and object's X-Z-area overlaps with the node's
-			X-Z-area.
-
-			Use 0.15*BS so that it is easier to get on a node.
-		*/
-		if (cbox.MaxEdge.X - d > box.MinEdge.X && cbox.MinEdge.X + d < box.MaxEdge.X &&
-				cbox.MaxEdge.Z - d > box.MinEdge.Z &&
-				cbox.MinEdge.Z + d < box.MaxEdge.Z) {
-			if (is_step_up[boxindex]) {
-				pos_f->Y += (cbox.MaxEdge.Y - box.MinEdge.Y);
-				box = box_0;
-				box.MinEdge += *pos_f;
-				box.MaxEdge += *pos_f;
-			}
-			if (fabs(cbox.MaxEdge.Y - box.MinEdge.Y) < 0.15 * BS) {
-				result.touching_ground = true;
-
-				if (is_object[boxindex])
-					result.standing_on_object = true;
-				if (is_unloaded[boxindex])
-					result.standing_on_unloaded = true;
-			}
-		}
-	}
-
 	return result;
 }