159 lines
3.8 KiB
C++
159 lines
3.8 KiB
C++
#include "ProximityGrid.h"
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#include "Box.inl"
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#include "Morton.h"
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using namespace nv;
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ProximityGrid::ProximityGrid() {
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}
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void ProximityGrid::reset() {
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cellArray.clear();
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}
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void ProximityGrid::init(const Array<Vector3> & pointArray) {
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// Compute bounding box.
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Box box;
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box.clearBounds();
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const uint count = pointArray.count();
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for (uint i = 0; i < count; i++) {
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box.addPointToBounds(pointArray[i]);
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}
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init(box, count);
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// Insert all points.
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for (uint i = 0; i < count; i++) {
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add(pointArray[i], i);
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}
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}
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void ProximityGrid::init(const Box & box, uint count) {
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reset();
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// Determine grid size.
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float cellWidth;
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Vector3 diagonal = box.extents() * 2.f;
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float volume = box.volume();
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if (equal(volume, 0)) {
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// Degenerate box, treat like a quad.
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Vector2 quad;
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if (diagonal.x < diagonal.y && diagonal.x < diagonal.z) {
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quad.x = diagonal.y;
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quad.y = diagonal.z;
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}
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else if (diagonal.y < diagonal.x && diagonal.y < diagonal.z) {
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quad.x = diagonal.x;
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quad.y = diagonal.z;
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}
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else {
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quad.x = diagonal.x;
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quad.y = diagonal.y;
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}
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float cellArea = quad.x * quad.y / count;
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cellWidth = sqrtf(cellArea); // pow(cellArea, 1.0f / 2.0f);
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}
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else {
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// Ideally we want one cell per point.
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float cellVolume = volume / count;
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cellWidth = pow(cellVolume, 1.0f / 3.0f);
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}
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nvDebugCheck(cellWidth != 0);
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sx = max(1, ftoi_ceil(diagonal.x / cellWidth));
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sy = max(1, ftoi_ceil(diagonal.y / cellWidth));
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sz = max(1, ftoi_ceil(diagonal.z / cellWidth));
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invCellSize.x = float(sx) / diagonal.x;
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invCellSize.y = float(sy) / diagonal.y;
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invCellSize.z = float(sz) / diagonal.z;
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cellArray.resize(sx * sy * sz);
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corner = box.minCorner; // @@ Align grid better?
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}
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// Gather all points inside the given sphere.
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// Radius is assumed to be small, so we don't bother culling the cells.
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void ProximityGrid::gather(const Vector3 & position, float radius, Array<uint> & indexArray) {
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int x0 = index_x(position.x - radius);
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int x1 = index_x(position.x + radius);
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int y0 = index_y(position.y - radius);
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int y1 = index_y(position.y + radius);
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int z0 = index_z(position.z - radius);
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int z1 = index_z(position.z + radius);
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for (int z = z0; z <= z1; z++) {
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for (int y = y0; y <= y1; y++) {
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for (int x = x0; x <= x1; x++) {
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int idx = index(x, y, z);
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indexArray.append(cellArray[idx].indexArray);
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}
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}
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}
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}
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uint32 ProximityGrid::mortonCount() const {
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uint64 s = U64(max3(sx, sy, sz));
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s = nextPowerOfTwo(s);
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if (s > 1024) {
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return U32(s * s * min3(sx, sy, sz));
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}
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return U32(s * s * s);
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}
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int ProximityGrid::mortonIndex(uint32 code) const {
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uint32 x, y, z;
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uint s = U32(max3(sx, sy, sz));
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if (s > 1024) {
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// Use layered two-dimensional morton order.
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s = nextPowerOfTwo(s);
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uint layer = code / (s * s);
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code = code % (s * s);
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uint layer_count = U32(min3(sx, sy, sz));
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if (sx == layer_count) {
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x = layer;
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y = decodeMorton2X(code);
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z = decodeMorton2Y(code);
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}
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else if (sy == layer_count) {
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x = decodeMorton2Y(code);
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y = layer;
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z = decodeMorton2X(code);
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}
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else /*if (sz == layer_count)*/ {
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x = decodeMorton2X(code);
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y = decodeMorton2Y(code);
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z = layer;
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}
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}
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else {
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x = decodeMorton3X(code);
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y = decodeMorton3Y(code);
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z = decodeMorton3Z(code);
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}
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if (x >= U32(sx) || y >= U32(sy) || z >= U32(sz)) {
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return -1;
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}
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return index(x, y, z);
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}
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