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Diffstat (limited to 'source/game/StarCollisionGenerator.cpp')
| -rw-r--r-- | source/game/StarCollisionGenerator.cpp | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/source/game/StarCollisionGenerator.cpp b/source/game/StarCollisionGenerator.cpp new file mode 100644 index 0000000..d7606dd --- /dev/null +++ b/source/game/StarCollisionGenerator.cpp @@ -0,0 +1,233 @@ +#include "StarCollisionGenerator.hpp" + +namespace Star { + +void CollisionGenerator::init(CollisionKindAccessor accessor) { + m_accessor = accessor; +} + +List<CollisionBlock> CollisionGenerator::getBlocks(RectI const& region) const { + if (region.isNull()) + return {}; + + List<CollisionBlock> list; + + populateCollisionBuffer(region); + + getBlocksMarchingSquares(list, region, CollisionKind::Dynamic); + getBlocksPlatforms(list, region, CollisionKind::Platform); + + return list; +} + +void CollisionGenerator::getBlocksPlatforms(List<CollisionBlock>& list, RectI const& region, CollisionKind kind) const { + int xMin = region.xMin(); + int xMax = region.xMax(); + int yMin = region.yMin(); + int yMax = region.yMax(); + + for (int x = xMin; x < xMax; ++x) { + for (int y = yMin; y < yMax; ++y) { + if (collisionKind(x, y) == kind) { + auto addBlock = [&](PolyF::VertexList vertices) { + CollisionBlock block; + block.space = Vec2I(x, y); + block.kind = kind; + block.poly = PolyF(move(vertices)); + block.polyBounds = block.poly.boundBox(); + list.append(move(block)); + }; + + // This was once simple and elegant and made sense but then I made it + // match the actual platform rendering more closely and now it's a big + // shitty pile of special cases again. RIP. + + bool right = collisionKind(x + 1, y) == kind; + bool left = collisionKind(x - 1, y) == kind; + + bool downRight = collisionKind(x + 1, y - 1) == kind && collisionKind(x + 1, y) != kind; + bool downLeft = collisionKind(x - 1, y - 1) == kind && collisionKind(x - 1, y) != kind; + + bool upRight = collisionKind(x + 1, y + 1) == kind && !left && !right; + bool upLeft = collisionKind(x - 1, y + 1) == kind && !left && !right; + + bool above = collisionKind(x, y + 1) == kind; + bool below = collisionKind(x, y - 1) == kind; + + if (downRight && downLeft && upRight && upLeft) { + addBlock({Vec2F(x, y), Vec2F(x + 1, y + 1)}); + addBlock({Vec2F(x + 1, y), Vec2F(x, y + 1)}); + } else if (above && below) { + addBlock({Vec2F(x, y + 1), Vec2F(x + 1, y + 1)}); + } else if (upLeft && downLeft && !upRight && !downRight) { + addBlock({Vec2F(x + 1, y), Vec2F(x, y + 1)}); + } else if (upRight && downRight && !upLeft && !upRight) { + addBlock({Vec2F(x, y), Vec2F(x + 1, y + 1)}); + } else if (upRight && downLeft) { + addBlock({Vec2F(x, y), Vec2F(x + 1, y + 1)}); + + // special case block for connecting flat platform above + if (above && collisionKind(x + 1, y + 1) == kind) + addBlock({Vec2F(x + 1, y + 1), Vec2F(x + 2, y + 2)}); + } else if (upLeft && downRight) { + addBlock({Vec2F(x + 1, y), Vec2F(x, y + 1)}); + + // special case block for connecting flat platform above + if (above && collisionKind(x - 1, y + 1) == kind) + addBlock({Vec2F(x, y + 1), Vec2F(x - 1, y + 2)}); + } else if (above && !downRight && !downLeft) { + addBlock({Vec2F(x, y + 1), Vec2F(x + 1, y + 1)}); + } else if (upLeft && !upRight) { + addBlock({Vec2F(x + 1, y), Vec2F(x, y + 1)}); + } else if (upRight && !upLeft) { + addBlock({Vec2F(x, y), Vec2F(x + 1, y + 1)}); + } else if (downRight && (left || !below)) { + addBlock({Vec2F(x + 1, y), Vec2F(x, y + 1)}); + } else if (downLeft && (right || !below)) { + addBlock({Vec2F(x, y), Vec2F(x + 1, y + 1)}); + } else { + addBlock({Vec2F(x, y + 1), Vec2F(x + 1, y + 1)}); + } + } + } + } +} + +void CollisionGenerator::getBlocksMarchingSquares(List<CollisionBlock>& list, RectI const& region, CollisionKind kind) const { + + // uses binary masking to assign each group of 4 tiles a value between 0 and 15 + // with corners ul = 1, ur = 2, lr = 4, ll = 8 + + // points spaced at 0.5 around the edge of a 1x1 square, clockwise from bottom left, + // plus the center point for special cases + static Vec2F const msv[9] = { + Vec2F(0.5, 0.5), + Vec2F(0.5, 1.0), + Vec2F(0.5, 1.5), + Vec2F(1.0, 1.5), + Vec2F(1.5, 1.5), + Vec2F(1.5, 1.0), + Vec2F(1.5, 0.5), + Vec2F(1.0, 0.5), + Vec2F(1.0, 1.0) + }; + + // refers to vertex offset indices in msv, with 8 being no vertex + static unsigned const msp[22][6] = { + {9, 9, 9, 9, 9, 9}, + {1, 2, 3, 9, 9, 9}, + {3, 4, 5, 9, 9, 9}, + {1, 2, 4, 5, 9, 9}, + {7, 5, 6, 9, 9, 9}, + {1, 2, 3, 5, 6, 7}, + {7, 3, 4, 6, 9, 9}, + {1, 2, 4, 6, 7, 9}, + {0, 1, 7, 9, 9, 9}, + {0, 2, 3, 7, 9, 9}, + {0, 1, 3, 4, 5, 7}, + {0, 2, 4, 5, 7, 9}, + {0, 1, 5, 6, 9, 9}, + {0, 2, 3, 5, 6, 9}, + {0, 1, 3, 4, 6, 9}, + {0, 2, 4, 6, 9, 9}, + // special cases for squared off top corners + {5, 6, 7, 8, 9, 9}, // top left corner + {0, 1, 8, 7, 9, 9}, // top right corner + // special cases for hollowed out bottom corners + {0, 2, 3, 8, 9, 9}, // lower left corner part 1 + {0, 8, 5, 6, 9, 9}, // lower left corner part 2 + {0, 1, 8, 6, 9, 9}, // lower right corner part 1 + {6, 8, 3, 4, 9, 9} // lower right corner part 2 + }; + + auto addBlock = [&](int x, int y, uint8_t svi) { + CollisionBlock block; + block.space = Vec2I(x, y); + block.poly.clear(); + for (auto i : msp[svi]) { + if (i == 9) + break; + block.poly.add(Vec2F(x, y) + msv[i]); + } + block.polyBounds = block.poly.boundBox(); + block.kind = std::max({collisionKind(x, y), collisionKind(x + 1, y), collisionKind(x, y + 1), collisionKind(x + 1, y + 1)}); + list.append(move(block)); + }; + + int xMin = region.xMin(); + int xMax = region.xMax(); + int yMin = region.yMin(); + int yMax = region.yMax(); + + for (int x = xMin; x < xMax; ++x) { + for (int y = yMin; y < yMax; ++y) { + uint8_t neighborMask = 0; + if (collisionKind(x, y + 1) >= kind) + neighborMask |= 1; + if (collisionKind(x + 1, y + 1) >= kind) + neighborMask |= 2; + if (collisionKind(x + 1, y) >= kind) + neighborMask |= 4; + if (collisionKind(x, y) >= kind) + neighborMask |= 8; + + if (neighborMask == 4) { + if (collisionKind(x + 2, y) >= kind && + collisionKind(x + 2, y + 1) < kind && + collisionKind(x, y - 1) < kind) { + + addBlock(x, y, 16); + continue; + } + } else if (neighborMask == 8) { + if (collisionKind(x - 1, y) >= kind && + collisionKind(x - 1, y + 1) < kind && + collisionKind(x + 1, y - 1) < kind) { + + addBlock(x, y, 17); + continue; + } + } else if (neighborMask == 13) { + if (collisionKind(x, y + 2) >= kind && + collisionKind(x + 1, y + 2) < kind && + collisionKind(x + 2, y) >= kind) { + + addBlock(x, y, 18); + addBlock(x, y, 19); + continue; + } + } else if (neighborMask == 14) { + if (collisionKind(x, y + 2) < kind && + collisionKind(x + 1, y + 2) >= kind && + collisionKind(x - 1, y) >= kind) { + + addBlock(x, y, 20); + addBlock(x, y, 21); + continue; + } + } + + if (neighborMask != 0) + addBlock(x, y, neighborMask); + } + } +} + +void CollisionGenerator::populateCollisionBuffer(RectI const& region) const { + int xmin = region.xMin() - BlockInfluenceRadius; + int ymin = region.yMin() - BlockInfluenceRadius; + int xmax = region.xMax() + BlockInfluenceRadius; + int ymax = region.yMax() + BlockInfluenceRadius; + + m_collisionBufferCorner = {xmin, ymin}; + m_collisionBuffer.resize(xmax - xmin, ymax - ymin); + for (int x = xmin; x < xmax; ++x) + for (int y = ymin; y < ymax; ++y) + m_collisionBuffer(x - xmin, y - ymin) = m_accessor(x, y); +} + +CollisionKind CollisionGenerator::collisionKind(int x, int y) const { + return m_collisionBuffer(x - m_collisionBufferCorner[0], y - m_collisionBufferCorner[1]); +} + +} |