Optimize a little bit isBlockInSight, adjustDist & collisions (#7193)

nerzhul · web-flow · commit a90d27e1e23f · 2018-04-04T00:43:08.000+02:00
* Use constexpr + unroll some calculations to cache definitively some calculations
* Unroll some calls in collision code &amp; use a constref instead of a copy in one occurence
diff --git a/src/collision.cpp b/src/collision.cpp
@@ -322,9 +322,12 @@ collisionMoveResult collisionMoveSimple(Environment *env, IGameDef *gamedef,
 			}
 			std::vector<aabb3f> nodeboxes;
 			n.getCollisionBoxes(gamedef->ndef(), &nodeboxes, neighbors);
+
+			// Calculate float position only once
+			v3f posf = intToFloat(p, BS);
 			for (auto box : nodeboxes) {
-				box.MinEdge += intToFloat(p, BS);
-				box.MaxEdge += intToFloat(p, BS);
+				box.MinEdge += posf;
+				box.MaxEdge += posf;
 				cinfo.emplace_back(false, false, n_bouncy_value, p, box);
 			}
 		} else {
@@ -437,7 +440,7 @@ collisionMoveResult collisionMoveSimple(Environment *env, IGameDef *gamedef,
 			Go through every nodebox, find nearest collision
 		*/
 		for (u32 boxindex = 0; boxindex < cinfo.size(); boxindex++) {
-			NearbyCollisionInfo box_info = cinfo[boxindex];
+			const NearbyCollisionInfo &box_info = cinfo[boxindex];
 			// Ignore if already stepped up this nodebox.
 			if (box_info.is_step_up)
 				continue;
diff --git a/src/util/numeric.cpp b/src/util/numeric.cpp
@@ -108,7 +108,7 @@ bool isBlockInSight(v3s16 blockpos_b, v3f camera_pos, v3f camera_dir,
 {
 	// Maximum radius of a block.  The magic number is
 	// sqrt(3.0) / 2.0 in literal form.
-	const f32 block_max_radius = 0.866025403784 * MAP_BLOCKSIZE * BS;
+	static constexpr const f32 block_max_radius = 0.866025403784f * MAP_BLOCKSIZE * BS;
 
 	v3s16 blockpos_nodes = blockpos_b * MAP_BLOCKSIZE;
 
@@ -125,16 +125,16 @@ bool isBlockInSight(v3s16 blockpos_b, v3f camera_pos, v3f camera_dir,
 	// Total distance
 	f32 d = MYMAX(0, blockpos_relative.getLength() - block_max_radius);
 
-	if(distance_ptr)
+	if (distance_ptr)
 		*distance_ptr = d;
 
 	// If block is far away, it's not in sight
-	if(d > range)
+	if (d > range)
 		return false;
 
 	// If block is (nearly) touching the camera, don't
 	// bother validating further (that is, render it anyway)
-	if(d == 0)
+	if (d == 0)
 		return true;
 
 	// Adjust camera position, for purposes of computing the angle,
@@ -166,12 +166,13 @@ bool isBlockInSight(v3s16 blockpos_b, v3f camera_pos, v3f camera_dir,
 s16 adjustDist(s16 dist, float zoom_fov)
 {
 	// 1.775 ~= 72 * PI / 180 * 1.4, the default on the client
-	const float default_fov = 1.775f;
+	static constexpr const float default_fov = 1.775f / 2.0f;
 	// heuristic cut-off for zooming
-	if (zoom_fov > default_fov / 2.0f)
+	if (zoom_fov > default_fov)
 		return dist;
 
 	// new_dist = dist * ((1 - cos(FOV / 2)) / (1-cos(zoomFOV /2))) ^ (1/3)
-	return round(dist * std::cbrt((1.0f - std::cos(default_fov / 2.0f)) /
+	// note: FOV is calculated at compilation time
+	return round(dist * std::cbrt((1.0f - std::cos(default_fov)) /
 		(1.0f - std::cos(zoom_fov / 2.0f))));
 }
