diff options
Diffstat (limited to 'thirdparty/bullet/BulletCollision/CollisionShapes/btHeightfieldTerrainShape.cpp')
| -rw-r--r-- | thirdparty/bullet/BulletCollision/CollisionShapes/btHeightfieldTerrainShape.cpp | 490 |
1 files changed, 480 insertions, 10 deletions
diff --git a/thirdparty/bullet/BulletCollision/CollisionShapes/btHeightfieldTerrainShape.cpp b/thirdparty/bullet/BulletCollision/CollisionShapes/btHeightfieldTerrainShape.cpp index c85ce2498e..34ec2d8c45 100644 --- a/thirdparty/bullet/BulletCollision/CollisionShapes/btHeightfieldTerrainShape.cpp +++ b/thirdparty/bullet/BulletCollision/CollisionShapes/btHeightfieldTerrainShape.cpp @@ -71,8 +71,13 @@ void btHeightfieldTerrainShape::initialize( m_flipQuadEdges = flipQuadEdges; m_useDiamondSubdivision = false; m_useZigzagSubdivision = false; + m_flipTriangleWinding = false; m_upAxis = upAxis; m_localScaling.setValue(btScalar(1.), btScalar(1.), btScalar(1.)); + + m_vboundsChunkSize = 0; + m_vboundsGridWidth = 0; + m_vboundsGridLength = 0; // determine min/max axis-aligned bounding box (aabb) values switch (m_upAxis) @@ -108,6 +113,7 @@ void btHeightfieldTerrainShape::initialize( btHeightfieldTerrainShape::~btHeightfieldTerrainShape() { + clearAccelerator(); } void btHeightfieldTerrainShape::getAabb(const btTransform& t, btVector3& aabbMin, btVector3& aabbMax) const @@ -323,35 +329,44 @@ void btHeightfieldTerrainShape::processAllTriangles(btTriangleCallback* callback } } + // TODO If m_vboundsGrid is available, use it to determine if we really need to process this area + for (int j = startJ; j < endJ; j++) { for (int x = startX; x < endX; x++) { btVector3 vertices[3]; + int indices[3] = { 0, 1, 2 }; + if (m_flipTriangleWinding) + { + indices[0] = 2; + indices[2] = 0; + } + if (m_flipQuadEdges || (m_useDiamondSubdivision && !((j + x) & 1)) || (m_useZigzagSubdivision && !(j & 1))) { //first triangle - getVertex(x, j, vertices[0]); - getVertex(x, j + 1, vertices[1]); - getVertex(x + 1, j + 1, vertices[2]); + getVertex(x, j, vertices[indices[0]]); + getVertex(x, j + 1, vertices[indices[1]]); + getVertex(x + 1, j + 1, vertices[indices[2]]); callback->processTriangle(vertices, x, j); //second triangle // getVertex(x,j,vertices[0]);//already got this vertex before, thanks to Danny Chapman - getVertex(x + 1, j + 1, vertices[1]); - getVertex(x + 1, j, vertices[2]); + getVertex(x + 1, j + 1, vertices[indices[1]]); + getVertex(x + 1, j, vertices[indices[2]]); callback->processTriangle(vertices, x, j); } else { //first triangle - getVertex(x, j, vertices[0]); - getVertex(x, j + 1, vertices[1]); - getVertex(x + 1, j, vertices[2]); + getVertex(x, j, vertices[indices[0]]); + getVertex(x, j + 1, vertices[indices[1]]); + getVertex(x + 1, j, vertices[indices[2]]); callback->processTriangle(vertices, x, j); //second triangle - getVertex(x + 1, j, vertices[0]); + getVertex(x + 1, j, vertices[indices[0]]); //getVertex(x,j+1,vertices[1]); - getVertex(x + 1, j + 1, vertices[2]); + getVertex(x + 1, j + 1, vertices[indices[2]]); callback->processTriangle(vertices, x, j); } } @@ -373,3 +388,458 @@ const btVector3& btHeightfieldTerrainShape::getLocalScaling() const { return m_localScaling; } + +namespace +{ + struct GridRaycastState + { + int x; // Next quad coords + int z; + int prev_x; // Previous quad coords + int prev_z; + btScalar param; // Exit param for previous quad + btScalar prevParam; // Enter param for previous quad + btScalar maxDistanceFlat; + btScalar maxDistance3d; + }; +} + +// TODO Does it really need to take 3D vectors? +/// Iterates through a virtual 2D grid of unit-sized square cells, +/// and executes an action on each cell intersecting the given segment, ordered from begin to end. +/// Initially inspired by http://www.cse.yorku.ca/~amana/research/grid.pdf +template <typename Action_T> +void gridRaycast(Action_T& quadAction, const btVector3& beginPos, const btVector3& endPos, int indices[3]) +{ + GridRaycastState rs; + rs.maxDistance3d = beginPos.distance(endPos); + if (rs.maxDistance3d < 0.0001) + { + // Consider the ray is too small to hit anything + return; + } + + + btScalar rayDirectionFlatX = endPos[indices[0]] - beginPos[indices[0]]; + btScalar rayDirectionFlatZ = endPos[indices[2]] - beginPos[indices[2]]; + rs.maxDistanceFlat = btSqrt(rayDirectionFlatX * rayDirectionFlatX + rayDirectionFlatZ * rayDirectionFlatZ); + + if (rs.maxDistanceFlat < 0.0001) + { + // Consider the ray vertical + rayDirectionFlatX = 0; + rayDirectionFlatZ = 0; + } + else + { + rayDirectionFlatX /= rs.maxDistanceFlat; + rayDirectionFlatZ /= rs.maxDistanceFlat; + } + + const int xiStep = rayDirectionFlatX > 0 ? 1 : rayDirectionFlatX < 0 ? -1 : 0; + const int ziStep = rayDirectionFlatZ > 0 ? 1 : rayDirectionFlatZ < 0 ? -1 : 0; + + const float infinite = 9999999; + const btScalar paramDeltaX = xiStep != 0 ? 1.f / btFabs(rayDirectionFlatX) : infinite; + const btScalar paramDeltaZ = ziStep != 0 ? 1.f / btFabs(rayDirectionFlatZ) : infinite; + + // pos = param * dir + btScalar paramCrossX; // At which value of `param` we will cross a x-axis lane? + btScalar paramCrossZ; // At which value of `param` we will cross a z-axis lane? + + // paramCrossX and paramCrossZ are initialized as being the first cross + // X initialization + if (xiStep != 0) + { + if (xiStep == 1) + { + paramCrossX = (ceil(beginPos[indices[0]]) - beginPos[indices[0]]) * paramDeltaX; + } + else + { + paramCrossX = (beginPos[indices[0]] - floor(beginPos[indices[0]])) * paramDeltaX; + } + } + else + { + paramCrossX = infinite; // Will never cross on X + } + + // Z initialization + if (ziStep != 0) + { + if (ziStep == 1) + { + paramCrossZ = (ceil(beginPos[indices[2]]) - beginPos[indices[2]]) * paramDeltaZ; + } + else + { + paramCrossZ = (beginPos[indices[2]] - floor(beginPos[indices[2]])) * paramDeltaZ; + } + } + else + { + paramCrossZ = infinite; // Will never cross on Z + } + + rs.x = static_cast<int>(floor(beginPos[indices[0]])); + rs.z = static_cast<int>(floor(beginPos[indices[2]])); + + // Workaround cases where the ray starts at an integer position + if (paramCrossX == 0.0) + { + paramCrossX += paramDeltaX; + // If going backwards, we should ignore the position we would get by the above flooring, + // because the ray is not heading in that direction + if (xiStep == -1) + { + rs.x -= 1; + } + } + + if (paramCrossZ == 0.0) + { + paramCrossZ += paramDeltaZ; + if (ziStep == -1) + rs.z -= 1; + } + + rs.prev_x = rs.x; + rs.prev_z = rs.z; + rs.param = 0; + + while (true) + { + rs.prev_x = rs.x; + rs.prev_z = rs.z; + rs.prevParam = rs.param; + + if (paramCrossX < paramCrossZ) + { + // X lane + rs.x += xiStep; + // Assign before advancing the param, + // to be in sync with the initialization step + rs.param = paramCrossX; + paramCrossX += paramDeltaX; + } + else + { + // Z lane + rs.z += ziStep; + rs.param = paramCrossZ; + paramCrossZ += paramDeltaZ; + } + + if (rs.param > rs.maxDistanceFlat) + { + rs.param = rs.maxDistanceFlat; + quadAction(rs); + break; + } + else + { + quadAction(rs); + } + } +} + +struct ProcessTrianglesAction +{ + const btHeightfieldTerrainShape* shape; + bool flipQuadEdges; + bool useDiamondSubdivision; + int width; + int length; + btTriangleCallback* callback; + + void exec(int x, int z) const + { + if (x < 0 || z < 0 || x >= width || z >= length) + { + return; + } + + btVector3 vertices[3]; + + // TODO Since this is for raycasts, we could greatly benefit from an early exit on the first hit + + // Check quad + if (flipQuadEdges || (useDiamondSubdivision && (((z + x) & 1) > 0))) + { + // First triangle + shape->getVertex(x, z, vertices[0]); + shape->getVertex(x + 1, z, vertices[1]); + shape->getVertex(x + 1, z + 1, vertices[2]); + callback->processTriangle(vertices, x, z); + + // Second triangle + shape->getVertex(x, z, vertices[0]); + shape->getVertex(x + 1, z + 1, vertices[1]); + shape->getVertex(x, z + 1, vertices[2]); + callback->processTriangle(vertices, x, z); + } + else + { + // First triangle + shape->getVertex(x, z, vertices[0]); + shape->getVertex(x, z + 1, vertices[1]); + shape->getVertex(x + 1, z, vertices[2]); + callback->processTriangle(vertices, x, z); + + // Second triangle + shape->getVertex(x + 1, z, vertices[0]); + shape->getVertex(x, z + 1, vertices[1]); + shape->getVertex(x + 1, z + 1, vertices[2]); + callback->processTriangle(vertices, x, z); + } + } + + void operator()(const GridRaycastState& bs) const + { + exec(bs.prev_x, bs.prev_z); + } +}; + +struct ProcessVBoundsAction +{ + const btAlignedObjectArray<btHeightfieldTerrainShape::Range>& vbounds; + int width; + int length; + int chunkSize; + + btVector3 rayBegin; + btVector3 rayEnd; + btVector3 rayDir; + + int* m_indices; + ProcessTrianglesAction processTriangles; + + ProcessVBoundsAction(const btAlignedObjectArray<btHeightfieldTerrainShape::Range>& bnd, int* indices) + : vbounds(bnd), + m_indices(indices) + { + } + void operator()(const GridRaycastState& rs) const + { + int x = rs.prev_x; + int z = rs.prev_z; + + if (x < 0 || z < 0 || x >= width || z >= length) + { + return; + } + + const btHeightfieldTerrainShape::Range chunk = vbounds[x + z * width]; + + btVector3 enterPos; + btVector3 exitPos; + + if (rs.maxDistanceFlat > 0.0001) + { + btScalar flatTo3d = chunkSize * rs.maxDistance3d / rs.maxDistanceFlat; + btScalar enterParam3d = rs.prevParam * flatTo3d; + btScalar exitParam3d = rs.param * flatTo3d; + enterPos = rayBegin + rayDir * enterParam3d; + exitPos = rayBegin + rayDir * exitParam3d; + + // We did enter the flat projection of the AABB, + // but we have to check if we intersect it on the vertical axis + if (enterPos[1] > chunk.max && exitPos[m_indices[1]] > chunk.max) + { + return; + } + if (enterPos[1] < chunk.min && exitPos[m_indices[1]] < chunk.min) + { + return; + } + } + else + { + // Consider the ray vertical + // (though we shouldn't reach this often because there is an early check up-front) + enterPos = rayBegin; + exitPos = rayEnd; + } + + gridRaycast(processTriangles, enterPos, exitPos, m_indices); + // Note: it could be possible to have more than one grid at different levels, + // to do this there would be a branch using a pointer to another ProcessVBoundsAction + } +}; + +// TODO How do I interrupt the ray when there is a hit? `callback` does not return any result +/// Performs a raycast using a hierarchical Bresenham algorithm. +/// Does not allocate any memory by itself. +void btHeightfieldTerrainShape::performRaycast(btTriangleCallback* callback, const btVector3& raySource, const btVector3& rayTarget) const +{ + // Transform to cell-local + btVector3 beginPos = raySource / m_localScaling; + btVector3 endPos = rayTarget / m_localScaling; + beginPos += m_localOrigin; + endPos += m_localOrigin; + + ProcessTrianglesAction processTriangles; + processTriangles.shape = this; + processTriangles.flipQuadEdges = m_flipQuadEdges; + processTriangles.useDiamondSubdivision = m_useDiamondSubdivision; + processTriangles.callback = callback; + processTriangles.width = m_heightStickWidth - 1; + processTriangles.length = m_heightStickLength - 1; + + // TODO Transform vectors to account for m_upAxis + int indices[3] = { 0, 1, 2 }; + if (m_upAxis == 2) + { + indices[1] = 2; + indices[2] = 1; + } + int iBeginX = static_cast<int>(floor(beginPos[indices[0]])); + int iBeginZ = static_cast<int>(floor(beginPos[indices[2]])); + int iEndX = static_cast<int>(floor(endPos[indices[0]])); + int iEndZ = static_cast<int>(floor(endPos[indices[2]])); + + if (iBeginX == iEndX && iBeginZ == iEndZ) + { + // The ray will never cross quads within the plane, + // so directly process triangles within one quad + // (typically, vertical rays should end up here) + processTriangles.exec(iBeginX, iEndZ); + return; + } + + + + if (m_vboundsGrid.size()==0) + { + // Process all quads intersecting the flat projection of the ray + gridRaycast(processTriangles, beginPos, endPos, &indices[0]); + } + else + { + btVector3 rayDiff = endPos - beginPos; + btScalar flatDistance2 = rayDiff[indices[0]] * rayDiff[indices[0]] + rayDiff[indices[2]] * rayDiff[indices[2]]; + if (flatDistance2 < m_vboundsChunkSize * m_vboundsChunkSize) + { + // Don't use chunks, the ray is too short in the plane + gridRaycast(processTriangles, beginPos, endPos, &indices[0]); + } + + ProcessVBoundsAction processVBounds(m_vboundsGrid, &indices[0]); + processVBounds.width = m_vboundsGridWidth; + processVBounds.length = m_vboundsGridLength; + processVBounds.rayBegin = beginPos; + processVBounds.rayEnd = endPos; + processVBounds.rayDir = rayDiff.normalized(); + processVBounds.processTriangles = processTriangles; + processVBounds.chunkSize = m_vboundsChunkSize; + // The ray is long, run raycast on a higher-level grid + gridRaycast(processVBounds, beginPos / m_vboundsChunkSize, endPos / m_vboundsChunkSize, indices); + } +} + +/// Builds a grid data structure storing the min and max heights of the terrain in chunks. +/// if chunkSize is zero, that accelerator is removed. +/// If you modify the heights, you need to rebuild this accelerator. +void btHeightfieldTerrainShape::buildAccelerator(int chunkSize) +{ + if (chunkSize <= 0) + { + clearAccelerator(); + return; + } + + m_vboundsChunkSize = chunkSize; + int nChunksX = m_heightStickWidth / chunkSize; + int nChunksZ = m_heightStickLength / chunkSize; + + if (m_heightStickWidth % chunkSize > 0) + { + ++nChunksX; // In case terrain size isn't dividable by chunk size + } + if (m_heightStickLength % chunkSize > 0) + { + ++nChunksZ; + } + + if (m_vboundsGridWidth != nChunksX || m_vboundsGridLength != nChunksZ) + { + clearAccelerator(); + m_vboundsGridWidth = nChunksX; + m_vboundsGridLength = nChunksZ; + } + + if (nChunksX == 0 || nChunksZ == 0) + { + return; + } + + // This data structure is only reallocated if the required size changed + m_vboundsGrid.resize(nChunksX * nChunksZ); + + // Compute min and max height for all chunks + for (int cz = 0; cz < nChunksZ; ++cz) + { + int z0 = cz * chunkSize; + + for (int cx = 0; cx < nChunksX; ++cx) + { + int x0 = cx * chunkSize; + + Range r; + + r.min = getRawHeightFieldValue(x0, z0); + r.max = r.min; + + // Compute min and max height for this chunk. + // We have to include one extra cell to account for neighbors. + // Here is why: + // Say we have a flat terrain, and a plateau that fits a chunk perfectly. + // + // Left Right + // 0---0---0---1---1---1 + // | | | | | | + // 0---0---0---1---1---1 + // | | | | | | + // 0---0---0---1---1---1 + // x + // + // If the AABB for the Left chunk did not share vertices with the Right, + // then we would fail collision tests at x due to a gap. + // + for (int z = z0; z < z0 + chunkSize + 1; ++z) + { + if (z >= m_heightStickLength) + { + continue; + } + + for (int x = x0; x < x0 + chunkSize + 1; ++x) + { + if (x >= m_heightStickWidth) + { + continue; + } + + btScalar height = getRawHeightFieldValue(x, z); + + if (height < r.min) + { + r.min = height; + } + else if (height > r.max) + { + r.max = height; + } + } + } + + m_vboundsGrid[cx + cz * nChunksX] = r; + } + } +} + +void btHeightfieldTerrainShape::clearAccelerator() +{ + m_vboundsGrid.clear(); +}
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