+ for (auto &i : m_drawlist) {
+ MapBlock *block = i.second;
+ block->refDrop();
+ }
+ m_drawlist.clear();
+
+ v3s16 cam_pos_nodes = floatToInt(m_camera_position, BS);
+
+ v3s16 p_blocks_min;
+ v3s16 p_blocks_max;
+ getBlocksInViewRange(cam_pos_nodes, &p_blocks_min, &p_blocks_max);
+
+ // Number of blocks occlusion culled
+ u32 blocks_occlusion_culled = 0;
+ // Blocks visited by the algorithm
+ u32 blocks_visited = 0;
+ // Block sides that were not traversed
+ u32 sides_skipped = 0;
+
+ // No occlusion culling when free_move is on and camera is inside ground
+ bool occlusion_culling_enabled = true;
+ if (m_control.allow_noclip) {
+ MapNode n = getNode(cam_pos_nodes);
+ if (n.getContent() == CONTENT_IGNORE || m_nodedef->get(n).solidness == 2)
+ occlusion_culling_enabled = false;
+ }
+
+ v3s16 camera_block = getContainerPos(cam_pos_nodes, MAP_BLOCKSIZE);
+ m_drawlist = std::map<v3s16, MapBlock*, MapBlockComparer>(MapBlockComparer(camera_block));
+
+ auto is_frustum_culled = m_client->getCamera()->getFrustumCuller();
+
+ // Uncomment to debug occluded blocks in the wireframe mode
+ // TODO: Include this as a flag for an extended debugging setting
+ // if (occlusion_culling_enabled && m_control.show_wireframe)
+ // occlusion_culling_enabled = porting::getTimeS() & 1;
+
+ std::queue<v3s16> blocks_to_consider;
+
+ // Bits per block:
+ // [ visited | 0 | 0 | 0 | 0 | Z visible | Y visible | X visible ]
+ MapBlockFlags blocks_seen(p_blocks_min, p_blocks_max);
+
+ // Start breadth-first search with the block the camera is in
+ blocks_to_consider.push(camera_block);
+ blocks_seen.getChunk(camera_block).getBits(camera_block) = 0x07; // mark all sides as visible
+
+ // Recursively walk the space and pick mapblocks for drawing
+ while (blocks_to_consider.size() > 0) {
+
+ v3s16 block_coord = blocks_to_consider.front();
+ blocks_to_consider.pop();
+
+ auto &flags = blocks_seen.getChunk(block_coord).getBits(block_coord);
+
+ // Only visit each block once (it may have been queued up to three times)
+ if ((flags & 0x80) == 0x80)
+ continue;
+ flags |= 0x80;
+
+ blocks_visited++;
+
+ // Get the sector, block and mesh
+ MapSector *sector = this->getSectorNoGenerate(v2s16(block_coord.X, block_coord.Z));
+
+ if (!sector)
+ continue;
+
+ MapBlock *block = sector->getBlockNoCreateNoEx(block_coord.Y);
+
+ MapBlockMesh *mesh = block ? block->mesh : nullptr;
+
+
+ // Calculate the coordinates for range and frutum culling
+ v3f mesh_sphere_center;
+ f32 mesh_sphere_radius;
+
+ v3s16 block_pos_nodes = block_coord * MAP_BLOCKSIZE;
+
+ if (mesh) {
+ mesh_sphere_center = intToFloat(block_pos_nodes, BS)
+ + mesh->getBoundingSphereCenter();
+ mesh_sphere_radius = mesh->getBoundingRadius();
+ }
+ else {
+ mesh_sphere_center = intToFloat(block_pos_nodes, BS) + v3f((MAP_BLOCKSIZE * 0.5f - 0.5f) * BS);
+ mesh_sphere_radius = 0.0f;
+ }
+
+ // First, perform a simple distance check.
+ if (!m_control.range_all &&
+ mesh_sphere_center.getDistanceFrom(intToFloat(cam_pos_nodes, BS)) >
+ m_control.wanted_range * BS + mesh_sphere_radius)
+ continue; // Out of range, skip.
+
+ // Frustum culling
+ // Only do coarse culling here, to account for fast camera movement.
+ // This is needed because this function is not called every frame.
+ float frustum_cull_extra_radius = 300.0f;
+ if (is_frustum_culled(mesh_sphere_center,
+ mesh_sphere_radius + frustum_cull_extra_radius))
+ continue;
+
+ // Calculate the vector from the camera block to the current block
+ // We use it to determine through which sides of the current block we can continue the search
+ v3s16 look = block_coord - camera_block;
+
+ // Occluded near sides will further occlude the far sides
+ u8 visible_outer_sides = flags & 0x07;
+
+ // Raytraced occlusion culling - send rays from the camera to the block's corners
+ if (occlusion_culling_enabled && m_enable_raytraced_culling &&
+ block && mesh &&
+ visible_outer_sides != 0x07 && isBlockOccluded(block, cam_pos_nodes)) {
+ blocks_occlusion_culled++;
+ continue;
+ }
+
+ // The block is visible, add to the draw list
+ if (mesh) {
+ // Add to set
+ block->refGrab();
+ m_drawlist[block_coord] = block;
+ }
+
+ // Decide which sides to traverse next or to block away
+
+ // First, find the near sides that would occlude the far sides
+ // * A near side can itself be occluded by a nearby block (the test above ^^)
+ // * A near side can be visible but fully opaque by itself (e.g. ground at the 0 level)
+
+ // mesh solid sides are +Z-Z+Y-Y+X-X
+ // if we are inside the block's coordinates on an axis,
+ // treat these sides as opaque, as they should not allow to reach the far sides
+ u8 block_inner_sides = (look.X == 0 ? 3 : 0) |
+ (look.Y == 0 ? 12 : 0) |
+ (look.Z == 0 ? 48 : 0);
+
+ // get the mask for the sides that are relevant based on the direction
+ u8 near_inner_sides = (look.X > 0 ? 1 : 2) |
+ (look.Y > 0 ? 4 : 8) |
+ (look.Z > 0 ? 16 : 32);
+
+ // This bitset is +Z-Z+Y-Y+X-X (See MapBlockMesh), and axis is XYZ.
+ // Get he block's transparent sides
+ u8 transparent_sides = (occlusion_culling_enabled && block) ? ~block->solid_sides : 0x3F;
+
+ // compress block transparent sides to ZYX mask of see-through axes
+ u8 near_transparency = (block_inner_sides == 0x3F) ? near_inner_sides : (transparent_sides & near_inner_sides);
+
+ // when we are inside the camera block, do not block any sides
+ if (block_inner_sides == 0x3F)
+ block_inner_sides = 0;
+
+ near_transparency &= ~block_inner_sides & 0x3F;
+
+ near_transparency |= (near_transparency >> 1);
+ near_transparency = (near_transparency & 1) |
+ ((near_transparency >> 1) & 2) |
+ ((near_transparency >> 2) & 4);
+
+ // combine with known visible sides that matter
+ near_transparency &= visible_outer_sides;
+
+ // The rule for any far side to be visible:
+ // * Any of the adjacent near sides is transparent (different axes)
+ // * The opposite near side (same axis) is transparent, if it is the dominant axis of the look vector
+
+ // Calculate vector from camera to mapblock center. Because we only need relation between
+ // coordinates we scale by 2 to avoid precision loss.
+ v3s16 precise_look = 2 * (block_pos_nodes - cam_pos_nodes) + MAP_BLOCKSIZE - 1;
+
+ // dominant axis flag
+ u8 dominant_axis = (abs(precise_look.X) > abs(precise_look.Y) && abs(precise_look.X) > abs(precise_look.Z)) |
+ ((abs(precise_look.Y) > abs(precise_look.Z) && abs(precise_look.Y) > abs(precise_look.X)) << 1) |
+ ((abs(precise_look.Z) > abs(precise_look.X) && abs(precise_look.Z) > abs(precise_look.Y)) << 2);
+
+ // Queue next blocks for processing:
+ // - Examine "far" sides of the current blocks, i.e. never move towards the camera
+ // - Only traverse the sides that are not occluded
+ // - Only traverse the sides that are not opaque
+ // When queueing, mark the relevant side on the next block as 'visible'
+ for (s16 axis = 0; axis < 3; axis++) {
+
+ // Select a bit from transparent_sides for the side
+ u8 far_side_mask = 1 << (2 * axis);
+
+ // axis flag
+ u8 my_side = 1 << axis;
+ u8 adjacent_sides = my_side ^ 0x07;
+
+ auto traverse_far_side = [&](s8 next_pos_offset) {
+ // far side is visible if adjacent near sides are transparent, or if opposite side on dominant axis is transparent
+ bool side_visible = ((near_transparency & adjacent_sides) | (near_transparency & my_side & dominant_axis)) != 0;
+ side_visible = side_visible && ((far_side_mask & transparent_sides) != 0);
+
+ v3s16 next_pos = block_coord;
+ next_pos[axis] += next_pos_offset;
+
+ // If a side is a see-through, mark the next block's side as visible, and queue
+ if (side_visible) {
+ auto &next_flags = blocks_seen.getChunk(next_pos).getBits(next_pos);
+ next_flags |= my_side;
+ blocks_to_consider.push(next_pos);
+ }
+ else {
+ sides_skipped++;
+ }
+ };
+
+
+ // Test the '-' direction of the axis
+ if (look[axis] <= 0 && block_coord[axis] > p_blocks_min[axis])
+ traverse_far_side(-1);
+
+ // Test the '+' direction of the axis
+ far_side_mask <<= 1;
+
+ if (look[axis] >= 0 && block_coord[axis] < p_blocks_max[axis])
+ traverse_far_side(+1);
+ }
+ }
+
+ g_profiler->avg("MapBlocks occlusion culled [#]", blocks_occlusion_culled);
+ g_profiler->avg("MapBlocks sides skipped [#]", sides_skipped);
+ g_profiler->avg("MapBlocks examined [#]", blocks_visited);
+ g_profiler->avg("MapBlocks drawn [#]", m_drawlist.size());