Implemented nearest neighbor downscaling (to be tested)

math/vector3i.h

@@ -90,12 +90,12 @@ struct Vector3i {
 		return coords[i];
 	}
 
+	// Clamps between min and max, where max is excluded
 	void clamp_to(const Vector3i min, const Vector3i max) {
 		if (x < min.x) x = min.x;
 		if (y < min.y) y = min.y;
 		if (z < min.z) z = min.z;
 
-		// TODO Not sure it should clamp like that...
 		if (x >= max.x) x = max.x - 1;
 		if (y >= max.y) y = max.y - 1;
 		if (z >= max.z) z = max.z - 1;

voxel_buffer.cpp

@@ -328,6 +328,54 @@ void VoxelBuffer::delete_channel(int i) {
 	channel.data = NULL;
 }
 
+void VoxelBuffer::downscale_to(VoxelBuffer &dst, Vector3i src_min, Vector3i src_max, Vector3i dst_min) const {
+
+	// TODO Align input to multiple of two
+
+	src_min.clamp_to(Vector3i(), _size);
+	src_max.clamp_to(Vector3i(), _size);
+
+	Vector3i dst_max = dst_min + (src_max - src_min) >> 2;
+
+	dst_min.clamp_to(Vector3i(), dst._size);
+	dst_max.clamp_to(Vector3i(), dst._size);
+
+	for (int channel_index = 0; channel_index < MAX_CHANNELS; ++channel_index) {
+
+		const Channel &src_channel = _channels[channel_index];
+		const Channel &dst_channel = _channels[channel_index];
+
+		if (src_channel.data == nullptr && dst_channel.data == nullptr && src_channel.defval == dst_channel.defval) {
+			// No action needed
+			continue;
+		}
+
+		// Nearest-neighbor downscaling
+
+		Vector3i pos;
+		for (pos.z = dst_min.z; pos.z < dst_max.z; ++pos.z) {
+			for (pos.x = dst_min.x; pos.x < dst_max.x; ++pos.x) {
+				for (pos.y = dst_min.y; pos.y < dst_max.y; ++pos.y) {
+
+					Vector3i src_pos = src_min + (pos - dst_min) << 2;
+
+					// TODO Remove check once it works
+					CRASH_COND(!validate_pos(src_pos.x, src_pos.y, src_pos.z));
+
+					int v;
+					if (src_channel.data) {
+						v = src_channel.data[index(src_pos.x, src_pos.y, src_pos.z)];
+					} else {
+						v = src_channel.defval;
+					}
+
+					dst.set_voxel(v, pos, channel_index);
+				}
+			}
+		}
+	}
+}
+
 void VoxelBuffer::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("create", "sx", "sy", "sz"), &VoxelBuffer::create);

voxel_buffer.h

@@ -118,6 +118,8 @@ public:
 
 	uint8_t *get_channel_raw(unsigned int channel_index) const;
 
+	void downscale_to(VoxelBuffer &dst, Vector3i src_min, Vector3i src_max, Vector3i dst_min) const;
+
 private:
 	void create_channel_noinit(int i, Vector3i size);
 	void create_channel(int i, Vector3i size, uint8_t defval);