Add parameter to skip the callback on the first tile.

For example if you are going from tile 1,1 to 1,2 you would get
two notifications if parInclFirst==true, one for 1,1 and one for
1,2. If parInclFirst==false, then you will only get a notification
for 1,2. Note that if the segment passed to to
for_each_voxel_under_segment() is too short and doesn't span over
the initial tile, passing parInclFirst==false will discard the
only callback you would normally get. Effectively this can be used
for a sort of "on tile changed" notification.

src/gamelib/character.cpp

@@ -93,7 +93,7 @@ namespace curry {
 			return true; //wtp.property->walkable;
 		};
 
-		for_each_voxel_under_segment(old_pos, this->position(), width_height(), *m_world, is_walkable);
+		for_each_voxel_under_segment(old_pos, this->position(), width_height(), *m_world, is_walkable, false);
 		//for (auto tile_vec : crossed_tiles(old_pos, this->position(), m_world->tile_size())) {
 		//	const TileIndex* const tile = m_world->tile(tile_vec);
 		//	for (uint16_t z = 0; z < m_world->layer_count(); ++z) {

src/gamelib/grid_raytrace.cpp

@@ -93,7 +93,14 @@ namespace curry {
 
 	//see:
 	//http://stackoverflow.com/questions/24679963/precise-subpixel-line-drawing-algorithm-rasterization-algorithm
-	void for_each_voxel_under_segment (const vec2f& parFrom, const vec2f& parTo, vec2us parObjSize, const WorldGrid& parWorld, std::function<bool(vec2us)> parFunc) {
+	void for_each_voxel_under_segment (
+		const vec2f& parFrom,
+		const vec2f& parTo,
+		vec2us parObjSize,
+		const WorldGrid& parWorld,
+		std::function<bool(vec2us)> parFunc,
+		bool parInclFirst
+	) {
 		const vec2f tile_size = vector_cast<vec2f>(parWorld.tile_size());
 		//in this simplified case everything should be part of the world grid
 		assert(parFrom >= vec2f(0.0f));
@@ -129,7 +136,12 @@ namespace curry {
 
 		vec2us curr_tile = pixel_to_world_tile(parWorld, u);
 		const vec2us last_tile = pixel_to_world_tile(parWorld, parTo);
-		while (parFunc(curr_tile) and last_tile != curr_tile) {
+		bool& do_callback = parInclFirst;
+		while (
+			((do_callback and parFunc(curr_tile)) or not do_callback)
+			and last_tile != curr_tile
+		) {
+			do_callback = true;
 			if (max.x() < max.y()) {
 				assert(step.x());
 				assert(

src/gamelib/grid_raytrace.hpp

@@ -30,5 +30,12 @@ namespace curry {
 	float segment_intersection (const vec2f& parA, const vec2f& parDirA, const vec2f& parB, const vec2f& parDirB);
 #endif
 
-	void for_each_voxel_under_segment ( const vec2f& parFrom, const vec2f& parTo, vec2us parObjSize, const WorldGrid& parWorld, std::function<bool(vec2us)> parFunc );
+	void for_each_voxel_under_segment (
+		const vec2f& parFrom,
+		const vec2f& parTo,
+		vec2us parObjSize,
+		const WorldGrid& parWorld,
+		std::function<bool(vec2us)> parFunc,
+		bool parInclFirst
+	);
 } //namespace curry

test/unit/grid_raytrace.cpp

@@ -54,7 +54,8 @@ TEST_CASE ("Check that 2D raytracing works", "[raytracing][geometry]") {
 			vec2f(639.0f, 639.0f), //to
 			vec2us(1, 1), //objsize
 			world, //world
-			[&diagonal](vec2us wtp) mutable {diagonal.push_back(wtp); return true;}
+			[&diagonal](vec2us wtp) mutable {diagonal.push_back(wtp); return true;},
+			true
 		);
 
 		const auto* tile_prop = &world.tile_property(world.tile(vec2us(0)));