Precision improvements (Part 5)

Get rid of floats when calculating chunk position from block position. This can be done in integers. Since CHUNK_WIDTH etc. are guaranteed to be powers of two, using & -N is equivalent to doing & ~(N-1), or put differently, making it divisible by N. That makes the division exact, and allows the compiler to transform it into a plain shift (tested with both gcc and clang).

We did the same in Part 3 of this series.

Author: Pedro Gimeno

common/source/world/World.cpp

@@ -31,9 +31,9 @@ bool World::isReloadRequested = false;
 
 Chunk *World::getChunkAtBlockPos(int x, int y, int z) const {
 	return getChunk(
-		std::floor((float)x / CHUNK_WIDTH),
-		std::floor((float)y / CHUNK_DEPTH),
-		std::floor((float)z / CHUNK_HEIGHT)
+		(x & -CHUNK_WIDTH)  / CHUNK_WIDTH,
+		(y & -CHUNK_DEPTH)  / CHUNK_DEPTH,
+		(z & -CHUNK_HEIGHT) / CHUNK_HEIGHT
 	);
 }