mapblock_mesh: Optimize a few things (#9713)

diff --git a/src/client/mapblock_mesh.cpp b/src/client/mapblock_mesh.cpp
index a5bee6b883cc284a52432d6e023a115655aa3ff6..0a1619b3fe4cb76e5d56eea0c914266c781892a5 100644 (file)
--- a/src/client/mapblock_mesh.cpp
+++ b/src/client/mapblock_mesh.cpp
@@ -225,7 +225,7 @@ static u16 getSmoothLightCombined(const v3s16 &p,
                return f.light_propagates;
        };
 
-       std::array<bool, 4> obstructed = {{ 1, 1, 1, 1 }};
+       bool obstructed[4] = { true, true, true, true };
        add_node(0);
        bool opaque1 = !add_node(1);
        bool opaque2 = !add_node(2);
@@ -372,6 +372,32 @@ void final_color_blend(video::SColor *result,
        Mesh generation helpers
 */
 
+// This table is moved outside getNodeVertexDirs to avoid the compiler using
+// a mutex to initialize this table at runtime right in the hot path.
+// For details search the internet for "cxa_guard_acquire".
+static const v3s16 vertex_dirs_table[] = {
+       // ( 1, 0, 0)
+       v3s16( 1,-1, 1), v3s16( 1,-1,-1),
+       v3s16( 1, 1,-1), v3s16( 1, 1, 1),
+       // ( 0, 1, 0)
+       v3s16( 1, 1,-1), v3s16(-1, 1,-1),
+       v3s16(-1, 1, 1), v3s16( 1, 1, 1),
+       // ( 0, 0, 1)
+       v3s16(-1,-1, 1), v3s16( 1,-1, 1),
+       v3s16( 1, 1, 1), v3s16(-1, 1, 1),
+       // invalid
+       v3s16(), v3s16(), v3s16(), v3s16(),
+       // ( 0, 0,-1)
+       v3s16( 1,-1,-1), v3s16(-1,-1,-1),
+       v3s16(-1, 1,-1), v3s16( 1, 1,-1),
+       // ( 0,-1, 0)
+       v3s16( 1,-1, 1), v3s16(-1,-1, 1),
+       v3s16(-1,-1,-1), v3s16( 1,-1,-1),
+       // (-1, 0, 0)
+       v3s16(-1,-1,-1), v3s16(-1,-1, 1),
+       v3s16(-1, 1, 1), v3s16(-1, 1,-1)
+};
+
 /*
        vertex_dirs: v3s16[4]
 */
@@ -384,44 +410,16 @@ static void getNodeVertexDirs(const v3s16 &dir, v3s16 *vertex_dirs)
                2: top-left
                3: top-right
        */
-       if (dir == v3s16(0, 0, 1)) {
-               // If looking towards z+, this is the face that is behind
-               // the center point, facing towards z+.
-               vertex_dirs[0] = v3s16(-1,-1, 1);
-               vertex_dirs[1] = v3s16( 1,-1, 1);
-               vertex_dirs[2] = v3s16( 1, 1, 1);
-               vertex_dirs[3] = v3s16(-1, 1, 1);
-       } else if (dir == v3s16(0, 0, -1)) {
-               // faces towards Z-
-               vertex_dirs[0] = v3s16( 1,-1,-1);
-               vertex_dirs[1] = v3s16(-1,-1,-1);
-               vertex_dirs[2] = v3s16(-1, 1,-1);
-               vertex_dirs[3] = v3s16( 1, 1,-1);
-       } else if (dir == v3s16(1, 0, 0)) {
-               // faces towards X+
-               vertex_dirs[0] = v3s16( 1,-1, 1);
-               vertex_dirs[1] = v3s16( 1,-1,-1);
-               vertex_dirs[2] = v3s16( 1, 1,-1);
-               vertex_dirs[3] = v3s16( 1, 1, 1);
-       } else if (dir == v3s16(-1, 0, 0)) {
-               // faces towards X-
-               vertex_dirs[0] = v3s16(-1,-1,-1);
-               vertex_dirs[1] = v3s16(-1,-1, 1);
-               vertex_dirs[2] = v3s16(-1, 1, 1);
-               vertex_dirs[3] = v3s16(-1, 1,-1);
-       } else if (dir == v3s16(0, 1, 0)) {
-               // faces towards Y+ (assume Z- as "down" in texture)
-               vertex_dirs[0] = v3s16( 1, 1,-1);
-               vertex_dirs[1] = v3s16(-1, 1,-1);
-               vertex_dirs[2] = v3s16(-1, 1, 1);
-               vertex_dirs[3] = v3s16( 1, 1, 1);
-       } else if (dir == v3s16(0, -1, 0)) {
-               // faces towards Y- (assume Z+ as "down" in texture)
-               vertex_dirs[0] = v3s16( 1,-1, 1);
-               vertex_dirs[1] = v3s16(-1,-1, 1);
-               vertex_dirs[2] = v3s16(-1,-1,-1);
-               vertex_dirs[3] = v3s16( 1,-1,-1);
-       }
+
+       // Direction must be (1,0,0), (-1,0,0), (0,1,0), (0,-1,0),
+       // (0,0,1), (0,0,-1)
+       assert(dir.X * dir.X + dir.Y * dir.Y + dir.Z * dir.Z == 1);
+
+       // Convert direction to single integer for table lookup
+       u8 idx = (dir.X + 2 * dir.Y + 3 * dir.Z) & 7;
+       idx = (idx - 1) * 4;
+
+       memcpy(vertex_dirs, &vertex_dirs_table[idx], 4 * sizeof(v3s16));
 }
 
 static void getNodeTextureCoords(v3f base, const v3f &scale, const v3s16 &dir, float *u, float *v)
@@ -892,6 +890,8 @@ static void updateFastFaceRow(
        u16 lights[4] = {0, 0, 0, 0};
        u8 waving;
        TileSpec tile;
+
+       // Get info of first tile
        getTileInfo(data, p, face_dir,
                        makes_face, p_corrected, face_dir_corrected,
                        lights, waving, tile);
@@ -902,8 +902,6 @@ static void updateFastFaceRow(
                // If tiling can be done, this is set to false in the next step
                bool next_is_different = true;
 
-               v3s16 p_next;
-
                bool next_makes_face = false;
                v3s16 next_p_corrected;
                v3s16 next_face_dir_corrected;
@@ -912,9 +910,9 @@ static void updateFastFaceRow(
                // If at last position, there is nothing to compare to and
                // the face must be drawn anyway
                if (j != MAP_BLOCKSIZE - 1) {
-                       p_next = p + translate_dir;
+                       p += translate_dir;
 
-                       getTileInfo(data, p_next, face_dir,
+                       getTileInfo(data, p, face_dir,
                                        next_makes_face, next_p_corrected,
                                        next_face_dir_corrected, next_lights,
                                        waving,
@@ -923,7 +921,7 @@ static void updateFastFaceRow(
                        if (next_makes_face == makes_face
                                        && next_p_corrected == p_corrected + translate_dir
                                        && next_face_dir_corrected == face_dir_corrected
-                                       && memcmp(next_lights, lights, ARRLEN(lights) * sizeof(u16)) == 0
+                                       && memcmp(next_lights, lights, sizeof(lights)) == 0
                                        // Don't apply fast faces to waving water.
                                        && (waving != 3 || !waving_liquids)
                                        && next_tile.isTileable(tile)) {
@@ -961,10 +959,9 @@ static void updateFastFaceRow(
                makes_face = next_makes_face;
                p_corrected = next_p_corrected;
                face_dir_corrected = next_face_dir_corrected;
-               std::memcpy(lights, next_lights, ARRLEN(lights) * sizeof(u16));
+               memcpy(lights, next_lights, sizeof(lights));
                if (next_is_different)
-                       tile = next_tile;
-               p = p_next;
+                       tile = std::move(next_tile); // faster than copy
        }
 }