Occlusion: Check for light_propagates and do mapblock bounds checks

3 files changed, 60 insertions, 34 deletions

diff --git a/src/client/clientmap.cpp b/src/client/clientmap.cpp
index f2db94296..3e4ab2e94 100644
--- a/src/client/clientmap.cpp
+++ b/src/client/clientmap.cpp
@@ -151,6 +151,11 @@ void ClientMap::updateDrawList()
 			occlusion_culling_enabled = false;
 	}
 
+	// 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;
+
 	for (const auto &sector_it : m_sectors) {
 		MapSector *sector = sector_it.second;
 		v2s16 sp = sector->getPos();
diff --git a/src/map.cpp b/src/map.cpp
index 3b57a9493..6b027d34b 100644
--- a/src/map.cpp
+++ b/src/map.cpp
@@ -1032,21 +1032,46 @@ void Map::removeNodeTimer(v3s16 p)
 	block->m_node_timers.remove(p_rel);
 }
 
-bool Map::isOccluded(v3s16 pos_origin, v3s16 pos_blockcenter, float step,
-	float stepfac, float offset, float end_offset, u32 needed_count)
+bool Map::isOccluded(const v3s16 &pos_camera, const v3s16 &pos_target,
+	const core::aabbox3d<s16> &block_bounds, float step, float stepfac, float offset,
+	u32 needed_count)
 {
-	float distance = BS * pos_origin.getDistanceFrom(pos_blockcenter);
-	v3f direction = intToFloat(pos_blockcenter - pos_origin, BS);
-	direction.normalize();
-	v3f pos_origin_f = intToFloat(pos_origin, BS);
+	// Worst-case safety distance to keep to the target position
+	// Anything smaller than the mapblock diagonal could result in in self-occlusion
+	// Diagonal = sqrt(1*1 + 1*1 + 1*1)
+	const static float BLOCK_DIAGONAL = BS * MAP_BLOCKSIZE * 1.732f;
 
+	v3f direction = intToFloat(pos_target - pos_camera, BS);
+	float distance = direction.getLength();
+
+	// Disable occlusion culling for near mapblocks in underground
+	if (distance < BLOCK_DIAGONAL)
+		return false;
+
+	// Normalize direction vector
+	if (distance > 0.0f)
+		direction /= distance;
+
+	v3f pos_origin_f = intToFloat(pos_camera, BS);
 	u32 count = 0;
-	for (; offset < distance + end_offset; offset += step){
-		v3f pf = pos_origin_f + direction * offset;
-		v3s16 pos_node = floatToInt(pf, BS);
-		MapNode node = getNode(pos_node);
-		if (m_nodedef->get(node).drawtype == NDT_NORMAL) {
-			// not transparent, see ContentFeature::updateTextures
+	bool is_valid_position;
+
+	for (; offset < distance; offset += step) {
+		v3f pos_node_f = pos_origin_f + direction * offset;
+		v3s16 pos_node = floatToInt(pos_node_f, BS);
+
+		if (offset > distance - BLOCK_DIAGONAL) {
+			// Do accurate position checks:
+			// Check whether the node is inside the current mapblock
+			if (block_bounds.isPointInside(pos_node))
+				return false;
+		}
+
+		MapNode node = getNode(pos_node, &is_valid_position);
+
+		if (is_valid_position &&
+				!m_nodedef->get(node).light_propagates) {
+			// Cannot see through light-blocking nodes --> occluded
 			count++;
 			if (count >= needed_count)
 				return true;
@@ -1058,8 +1083,11 @@ bool Map::isOccluded(v3s16 pos_origin, v3s16 pos_blockcenter, float step,
 
 bool Map::isBlockOccluded(MapBlock *block, v3s16 cam_pos_nodes)
 {
+	// Check occlusion for center and all 8 corners of the mapblock
+	// Overshoot a little for less flickering
 	static const s16 bs2 = MAP_BLOCKSIZE / 2 + 1;
-	static const v3s16 dir8[8] = {
+	static const v3s16 dir9[9] = {
+		v3s16( 0,  0,  0),
 		v3s16( 1,  1,  1) * bs2,
 		v3s16( 1,  1, -1) * bs2,
 		v3s16( 1, -1,  1) * bs2,
@@ -1070,34 +1098,26 @@ bool Map::isBlockOccluded(MapBlock *block, v3s16 cam_pos_nodes)
 		v3s16(-1, -1, -1) * bs2,
 	};
 
-	v3s16 pos_blockcenter = block->getPos() * MAP_BLOCKSIZE;
-	pos_blockcenter += v3s16(MAP_BLOCKSIZE) / 2;
+	// Minimal and maximal positions in the mapblock
+	core::aabbox3d<s16> block_bounds = block->getBox();
 
-	float step = BS * 1;
+	v3s16 pos_blockcenter = block_bounds.MinEdge + (MAP_BLOCKSIZE / 2);
+
+	// Starting step size, value between 1m and sqrt(3)m
+	float step = BS * 1.2f;
 	// Multiply step by each iteraction by 'stepfac' to reduce checks in distance
-	float stepfac = 1.1;
+	float stepfac = 1.05f;
 
-	float start_offset = BS * 1;
-	// The occlusion search of 'isOccluded()' must stop short of the target
-	// point by distance 'end_offset' (end offset) to not enter the target mapblock.
-	// For the 8 mapblock corners 'end_offset' must therefore be the maximum diagonal
-	// of a mapblock, because we must consider all view angles.
-	// sqrt(1^2 + 1^2 + 1^2) = 1.732
-	float end_offset = -BS * MAP_BLOCKSIZE * 1.7321;
+	float start_offset = BS * 1.0f;
 
 	// to reduce the likelihood of falsely occluded blocks
 	// require at least two solid blocks
 	// this is a HACK, we should think of a more precise algorithm
 	u32 needed_count = 2;
 
-	// For the central point of the mapblock 'end_offset' can be halved
-	if (!isOccluded(cam_pos_nodes, pos_blockcenter,
-			step, stepfac, start_offset, end_offset / 2.0f, needed_count))
-		return false;
-
-	for (const v3s16 &dir : dir8) {
-		if (!isOccluded(cam_pos_nodes, pos_blockcenter + dir,
-				step, stepfac, start_offset, end_offset, needed_count))
+	for (const v3s16 &dir : dir9) {
+		if (!isOccluded(cam_pos_nodes, pos_blockcenter + dir, block_bounds,
+				step, stepfac, start_offset, needed_count))
 			return false;
 	}
 	return true;
diff --git a/src/map.h b/src/map.h
index d26da37a6..232a25ac7 100644
--- a/src/map.h
+++ b/src/map.h
@@ -310,8 +310,9 @@ protected:
 	// This stores the properties of the nodes on the map.
 	const NodeDefManager *m_nodedef;
 
-	bool isOccluded(v3s16 pos_origin, v3s16 pos_blockcenter, float step,
-		float stepfac, float start_offset, float end_offset, u32 needed_count);
+	bool isOccluded(const v3s16 &pos_camera, const v3s16 &pos_target,
+		const core::aabbox3d<s16> &block_bounds, float step, float stepfac,
+		float offset, u32 needed_count);
 
 private:
 	f32 m_transforming_liquid_loop_count_multiplier = 1.0f;