diff options
| -rw-r--r-- | ray_marching.cginc | 139 |
1 files changed, 97 insertions, 42 deletions
diff --git a/ray_marching.cginc b/ray_marching.cginc index bf01eb4..9cb8dd0 100644 --- a/ray_marching.cginc +++ b/ray_marching.cginc @@ -46,65 +46,120 @@ float map(float3 p) { } #if defined(_RAY_MARCHING_HEX_GRID) -void hex_nearest_neighbors(float3 cubeId, float3 neighborDir, - out float3 id0, out float3 id1, out float3 id2) { - // Standard cube-coordinate neighbour offsets (sum equals zero). - const float3 axis0 = float3( 1.0f, 0.0f, -1.0f); - const float3 axis1 = float3( 0.0f, 1.0f, -1.0f); - const float3 axis2 = float3( 1.0f, -1.0f, 0.0f); - - const float3 cube0 = cubeId + axis0 * neighborDir.xxx; - const float3 cube1 = cubeId + axis1 * neighborDir.yyy; - const float3 cube2 = cubeId + axis2 * neighborDir.zzz; - - // Convert back to our "x = y + z" coordinate representation. - id0 = float3(cube0.x + cube0.y, cube0.x, cube0.y); - id1 = float3(cube1.x + cube1.y, cube1.x, cube1.y); - id2 = float3(cube2.x + cube2.y, cube2.x, cube2.y); -} - float domain_repeat_hex_grid(inout float3 p) { - float d; - - const float3 count = _Ray_Marching_Hex_Grid_Count * 0.5f; + const float gridCount = max(_Ray_Marching_Hex_Grid_Count, 1.0f); + const float halfCount = gridCount * 0.5f; + const float3 count = float3(halfCount, halfCount, halfCount); const float3 period = 1.0f / count; const float3 hex = cart_to_hex(p.xy); // Cell ID. const float3 id = round_hex(hex / period); // Coordinates within the current cell. const float3 local = hex - period * id; + float3 candidate = p; + candidate.xy = hex_to_cart(local); + float d = map(candidate); + float3 bestPos = candidate; +#if defined(_RAY_MARCHING_CORRECT_REPETITION) const float3 cubeId = float3(id.y, id.z, -id.y - id.z); - const float3 cubeLocal = float3(local.y, local.z, -local.y - local.z); - float3 neighborDir = sign(cubeLocal); - neighborDir += (1.0f.xxx - abs(neighborDir)); + const float limit = max((gridCount - 1.0f) * 0.5f, 0.0f); + const float3 cubeLimit = float3(limit, limit, limit); + if (any(abs(cubeId) > cubeLimit)) { + p = float3(1e9, 1e9, 1e9); + return 1e9; + } + const float3 cubeOffsets[6] = { + float3( 1.0f, -1.0f, 0.0f), + float3( 1.0f, 0.0f, -1.0f), + float3( 0.0f, 1.0f, -1.0f), + float3(-1.0f, 1.0f, 0.0f), + float3(-1.0f, 0.0f, 1.0f), + float3( 0.0f, -1.0f, 1.0f), + }; -#if defined(_RAY_MARCHING_CORRECT_REPETITION) - float3 ids[4]; - ids[0] = id; - hex_nearest_neighbors(cubeId, neighborDir, ids[1], ids[2], ids[3]); - const uint kNumCells = 4u; -#else - float3 ids[1]; - ids[0] = id; - const uint kNumCells = 1u; -#endif + float neighborDistSq[4] = { 1e9, 1e9, 1e9, 1e9 }; + float3 neighborIds[4] = { + float3(0.0f, 0.0f, 0.0f), + float3(0.0f, 0.0f, 0.0f), + float3(0.0f, 0.0f, 0.0f), + float3(0.0f, 0.0f, 0.0f)}; + float2 neighborLoc[4] = { + float2(0.0f, 0.0f), + float2(0.0f, 0.0f), + float2(0.0f, 0.0f), + float2(0.0f, 0.0f)}; - d = 1e9; - float3 bestPos = p; - for (uint ii = 0; ii < kNumCells; ++ii) { - const float3 rid = ids[ii]; - if (any(abs(rid) > count * 0.5f)) continue; + [unroll] + for (int idx = 0; idx < 6; ++idx) { + const float3 cube = cubeId + cubeOffsets[idx]; + const float3 rid = float3(cube.x + cube.y, cube.x, cube.y); + + if (any(abs(cube) > cubeLimit)) { + continue; + } - float3 candidate = p; - candidate.xy = hex_to_cart(hex - period * rid); + const float2 localXY = hex_to_cart(hex - period * rid); + const float distSq = dot(localXY, localXY); + + if (distSq >= neighborDistSq[3]) { + continue; + } + + neighborDistSq[3] = distSq; + neighborIds[3] = rid; + neighborLoc[3] = localXY; + + if (neighborDistSq[3] < neighborDistSq[2]) { + const float tmpDist = neighborDistSq[2]; + const float3 tmpId = neighborIds[2]; + const float2 tmpLoc = neighborLoc[2]; + neighborDistSq[2] = neighborDistSq[3]; + neighborIds[2] = neighborIds[3]; + neighborLoc[2] = neighborLoc[3]; + neighborDistSq[3] = tmpDist; + neighborIds[3] = tmpId; + neighborLoc[3] = tmpLoc; + } + if (neighborDistSq[2] < neighborDistSq[1]) { + const float tmpDist = neighborDistSq[1]; + const float3 tmpId = neighborIds[1]; + const float2 tmpLoc = neighborLoc[1]; + neighborDistSq[1] = neighborDistSq[2]; + neighborIds[1] = neighborIds[2]; + neighborLoc[1] = neighborLoc[2]; + neighborDistSq[2] = tmpDist; + neighborIds[2] = tmpId; + neighborLoc[2] = tmpLoc; + } + if (neighborDistSq[1] < neighborDistSq[0]) { + const float tmpDist = neighborDistSq[0]; + const float3 tmpId = neighborIds[0]; + const float2 tmpLoc = neighborLoc[0]; + neighborDistSq[0] = neighborDistSq[1]; + neighborIds[0] = neighborIds[1]; + neighborLoc[0] = neighborLoc[1]; + neighborDistSq[1] = tmpDist; + neighborIds[1] = tmpId; + neighborLoc[1] = tmpLoc; + } + } + + [unroll] + for (int idx = 0; idx < 4; ++idx) { + if (neighborDistSq[idx] >= 1e9) { + continue; + } - const float d_cur = map(candidate); + float3 neighbour = p; + neighbour.xy = neighborLoc[idx]; + const float d_cur = map(neighbour); if (d_cur < d) { d = d_cur; - bestPos = candidate; + bestPos = neighbour; } } +#endif // _RAY_MARCHING_CORRECT_REPETITION p = bestPos; return d; |