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#include "ChunkMeshing.hpp"
namespace MC::World::Generation {
std::array<Vector<2, F32>, 4> face_tex_coords(BlockType type, BlockSide side) {
U8 atlas_width = 4;
U8 atlas_height = 4;
Real width_step = 1.0f / atlas_width;
Real height_step = 1.0f / atlas_height;
auto block_coords = [=](U8 x, U8 y) {
auto t = y * height_step;
auto l = x * width_step;
auto b = t + height_step;
auto r = l + width_step;
return std::array<Vector<2, F32>, 4>{{
{l, b}, {r, b}, {r, t}, {l, t},
}};
};
switch (type) {
case BlockType::Dirt:
return block_coords(1, 0);
case BlockType::Grass:
switch (side) {
case BlockSide::Front:
case BlockSide::Back:
case BlockSide::Left:
case BlockSide::Right:
return block_coords(2, 0);
case BlockSide::Bottom:
return block_coords(1, 0);
case BlockSide::Top:
return block_coords(0, 0);
}
case BlockType::Stone:
return block_coords(3, 0);
case BlockType::Sand:
return block_coords(1, 1);
case BlockType::Water:
return block_coords(0, 1);
case BlockType::Snow:
switch (side) {
case BlockSide::Front:
case BlockSide::Back:
case BlockSide::Left:
case BlockSide::Right:
return block_coords(3, 1);
case BlockSide::Bottom:
return block_coords(1, 0);
case BlockSide::Top:
return block_coords(2, 1);
}
case BlockType::Wood:
switch (side) {
case BlockSide::Front:
case BlockSide::Back:
case BlockSide::Right:
case BlockSide::Left:
return block_coords(0, 2);
case BlockSide::Bottom:
case BlockSide::Top:
return block_coords(1, 2);
}
case BlockType::Leaves:
return block_coords(2, 2);
case BlockType::Air:
return {};
}
}
std::array<Vector<3, F32>, 4> face_normals(BlockSide side) {
auto is_side = [=](BlockSide s) -> Real { return s == side; };
Vector<3, F32> normal = {
is_side(BlockSide::Right) - is_side(BlockSide::Left),
is_side(BlockSide::Top) - is_side(BlockSide::Bottom),
is_side(BlockSide::Front) - is_side(BlockSide::Back),
};
return {normal, normal, normal, normal};
}
Bool is_face_visible(Chunk& chunk, const ChunkMeshing::ChunkNeighbors& neighbors, U32 x, U32 y, U32 z, BlockSide side) {
Vector<3, I32> offset{};
switch (side) {
case BlockSide::Front:
offset[2] = 1;
break;
case BlockSide::Back:
offset[2] = -1;
break;
case BlockSide::Top:
offset[1] = 1;
break;
case BlockSide::Bottom:
offset[1] = -1;
break;
case BlockSide::Left:
offset[0] = -1;
break;
case BlockSide::Right:
offset[0] = 1;
break;
}
Vector<3, I32> neighbor_pos{
(I32)x + offset.x(), (I32)y + offset.y(), (I32)z + offset.z(),
};
Chunk* chunk_to_ask;
if (neighbor_pos.z() < 0) {
chunk_to_ask = &neighbors.north;
neighbor_pos.z() += Chunk::Width;
} else if (neighbor_pos.x() >= (I32)Chunk::Width) {
chunk_to_ask = &neighbors.east;
neighbor_pos.x() -= Chunk::Width;
} else if (neighbor_pos.z() >= (I32)Chunk::Width) {
chunk_to_ask = &neighbors.south;
neighbor_pos.z() -= Chunk::Width;
} else if (neighbor_pos.x() < 0) {
chunk_to_ask = &neighbors.west;
neighbor_pos.x() += Chunk::Width;
} else {
chunk_to_ask = &chunk;
}
auto [neighbor] = chunk_to_ask->get(neighbor_pos.x(), neighbor_pos.y(), neighbor_pos.z());
return neighbor.is_transparent();
}
GFX::Mesh ChunkMeshing::create_mesh_for_chunk(Chunk& chunk, const ChunkNeighbors& neighbors) {
std::vector<Vector<3, F32>> positions{};
std::vector<Vector<3, F32>> normals{};
std::vector<Vector<2, F32>> tex_coords{};
std::vector<U32> indices{};
for (Int x = 0; x < Chunk::Width; x++) {
for (Int y = 0; y < Chunk::Height; y++) {
for (Int z = 0; z < Chunk::Width; z++) {
auto type = chunk.get(x, y, z).type;
if (type == BlockType::Air) {
continue;
}
for (auto side: BlockSide::all()) {
if (!is_face_visible(chunk, neighbors, x, y, z, side)) {
continue;
}
auto side_positions = side.face();
auto side_normals = face_normals(side);
auto side_tex_coords = face_tex_coords(type, side);
for (auto& position : side_positions) {
position = position + Vector<3, F32>{x, y, z};
}
U32 s = positions.size();
positions.insert(positions.end(), side_positions.begin(), side_positions.end());
normals.insert(normals.end(), side_normals.begin(), side_normals.end());
tex_coords.insert(tex_coords.end(), side_tex_coords.begin(), side_tex_coords.end());
indices.insert(indices.end(), {s, s + 1, s + 3, s + 1, s + 2, s + 3});
}
}
}
}
return {
{positions, normals, tex_coords},
indices,
};
}
}
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