Rewrite collision check loops, fix negative coordinates

Made the loops more robust by looping on integers instead of floats.

The cause for the need to fix negative coordinates was that world.getBlock() was being called with implied truncation towards zero, not with floor. Fixed.

client/source/world/ClientPlayer.cpp

@@ -162,44 +162,30 @@ void ClientPlayer::setPosition(double x, double y, double z) {
 }
 
 void ClientPlayer::checkCollisions(const ClientWorld &world) {
-#if defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__NT__) || defined(__ANDROID__)
-	const double PLAYER_HEIGHT = 1.8;
-	double eyeheight = m_z + PLAYER_HEIGHT - 1.4;
-	// testPoint(world, glm::dvec3(m_x, m_y, m_z), m_velocity);
-	testPoint(world, m_x - 0.2, m_y - 0.2, eyeheight - PLAYER_HEIGHT - 0.4, m_velocity);
-	testPoint(world, m_x + 0.2, m_y - 0.2, eyeheight - PLAYER_HEIGHT - 0.4, m_velocity);
-	testPoint(world, m_x - 0.2, m_y + 0.2, eyeheight - PLAYER_HEIGHT - 0.4, m_velocity);
-	testPoint(world, m_x + 0.2, m_y + 0.2, eyeheight - PLAYER_HEIGHT - 0.4, m_velocity);
-	testPoint(world, m_x - 0.2, m_y - 0.2, eyeheight - 0.4, m_velocity);
-	testPoint(world, m_x + 0.2, m_y - 0.2, eyeheight - 0.4, m_velocity);
-	testPoint(world, m_x - 0.2, m_y + 0.2, eyeheight - 0.4, m_velocity);
-	testPoint(world, m_x + 0.2, m_y + 0.2, eyeheight - 0.4, m_velocity);
-#else
-	for (double z = m_z + m_hitbox.z ; z <= m_z + (m_hitbox.z + m_hitbox.sizeZ) + 0.1 ; z += 0.9) {
-		for (double y = m_y + m_hitbox.y ; y <= m_y + (m_hitbox.y + m_hitbox.sizeY) + 0.1 ; y += 0.2) {
-			for (double x = m_x + m_hitbox.x ; x <= m_x + (m_hitbox.x + m_hitbox.sizeX) + 0.1 ; x += 0.2) {
-				if (x == m_x + m_hitbox.x || x == m_x + (m_hitbox.x + m_hitbox.sizeX)
-				 || y == m_y + m_hitbox.y || y == m_y + (m_hitbox.y + m_hitbox.sizeY)
-				 || z == m_z + m_hitbox.z || z == m_z + (m_hitbox.z + m_hitbox.sizeZ))
-					testPoint(world, x, y, z, m_velocity);
+	gk::Vector3d corner{m_x + m_hitbox.x, m_y + m_hitbox.y, m_z + m_hitbox.z};
+
+	constexpr int numPointsPerEdge = 3;
+	constexpr int lastPoint = numPointsPerEdge - 1;
+
+	for (int z = 0; z <= lastPoint; z++) {
+		for (int y = 0; y <= lastPoint; y++) {
+			for (int x = 0; x <= lastPoint; x++) {
+				if (x == 0 || x == lastPoint || y == 0 || y == lastPoint || z == 0 || z == lastPoint)
+					testPoint(world, corner.x + m_hitbox.sizeX * ((double)x / lastPoint),
+					          corner.y + m_hitbox.sizeY * ((double)y / lastPoint),
+					          corner.z + m_hitbox.sizeZ * ((double)z / lastPoint), m_velocity);
 			}
 		}
 	}
-#endif
 }
 
 bool passable(const ClientWorld &world, double x, double y, double z) {
-	u32 blockID = world.getBlock(x, y, z);
+	u32 blockID = world.getBlock(floor(x), floor(y), floor(z));
 	const Block &block = Registry::getInstance().getBlock(blockID);
 	return !blockID || block.drawType() == BlockDrawType::Liquid || block.drawType() == BlockDrawType::XShape;
 }
 
 void ClientPlayer::testPoint(const ClientWorld &world, double x, double y, double z, glm::dvec3 &vel) {
-	// FIXME: Temporary fix, find the real problem!!!
-	if (x < 1) --x;
-	if (y < 1) --y;
-	if (z < 1) --z;
-
 	if(!passable(world, x + vel.x, y, z)) vel.x = 0;
 	if(!passable(world, x, y + vel.y, z)) vel.y = 0;
 	if(!passable(world, x, y, z + vel.z)) {