97 lines
2.9 KiB
C#

// Copyright 2014-2017 ClassicalSharp | Licensed under BSD-3
#if OCCLUSION
using System;
using ClassicalSharp.GraphicsAPI;
namespace ClassicalSharp {
public partial class ChunkMeshBuilder {
unsafe int ComputeOcclusion() {
int* didFlags = stackalloc int[chunkSize2];
OpenTK.MemUtils.memset((IntPtr)didFlags, 0x00, 0, chunkSize2 * sizeof(int));
int* stack = stackalloc int[chunkSize3 * 4];
int i = 0;
bool solidX = true, solidY = true, solidZ = true;
for (int y = 0; y < 16; y++) {
for (int z = 0; z < 16; z++) {
int flagIndex = (y << 4) | z;
int chunkIndex = (y + 1) * extChunkSize2 + (z + 1) * extChunkSize + (0 + 1);
for (int x = 0; x < 16; x++) {
BlockID block = chunk[chunkIndex];
if (BlockInfo.FullOpaque[block]) {
didFlags[flagIndex] |= (1 << x);
} else if ((didFlags[flagIndex] & (1 << x)) == 0) {
FloodFill(didFlags, stack, i, ref solidX, ref solidY, ref solidZ);
}
i++;
chunkIndex++;
}
}
}
return (solidX ? 0x1 : 0) | (solidZ ? 0x2 : 0) | (solidY ? 0x4 : 0);
}
unsafe void FloodFill(int* didFlags, int* stack, int startIndex,
ref bool solidX, ref bool solidY, ref bool solidZ) {
int index = 0;
stack[index++] = startIndex;
bool tX0 = false, tX1 = false, tY0 = false,
tY1 = false, tZ0 = false, tZ1 = false;
while (index > 0) {
int bIndex = stack[--index];
int x = (bIndex & 0xF);
int z = ((bIndex >> 4) & 0xF);
int y = ((bIndex >> 8) & 0xF);
int flagIndex = (y << 4) | z;
didFlags[flagIndex] |= (1 << x);
int chunkIndex = (y + 1) * extChunkSize2 + (z + 1) * extChunkSize + (x + 1);
BlockID block = chunk[chunkIndex];
if (BlockInfo.Draw[block] != DrawType.Opaque) {
if (x == 0)
tX0 = true;
else if ((didFlags[flagIndex] & (1 << (x - 1))) == 0)
stack[index++] = bIndex - 1;
if (x == 15)
tX1 = true;
else if ((didFlags[flagIndex] & (1 << (x + 1))) == 0)
stack[index++] = bIndex + 1;
if (z == 0)
tZ0 = true;
else if ((didFlags[flagIndex - 1] & (1 << x)) == 0)
stack[index++] = bIndex - 16;
if (z == 15)
tZ1 = true;
else if ((didFlags[flagIndex + 1] & (1 << x)) == 0)
stack[index++] = bIndex + 16;
}
if (!BlockInfo.IsOpaqueY[block]) {
if (y == 0)
tY0 = true;
else if ((didFlags[flagIndex - 16] & (1 << x)) == 0
&& !BlockInfo.IsOpaqueY[chunk[chunkIndex - extChunkSize2]])
stack[index++] = bIndex - 256;
if (y == 15)
tY1 = true;
else if ((didFlags[flagIndex + 16] & (1 << x)) == 0
&& !BlockInfo.IsOpaqueY[chunk[chunkIndex + extChunkSize2]])
stack[index++] = bIndex + 256;
}
}
if (tX0 && tX1) solidX = false;
if (tY0 && tY1) solidY = false;
if (tZ0 && tZ1) solidZ = false;
}
}
}
#endif