From 4bcc55ad344811f15c570ca7a4bb0c46ab1e4f7f Mon Sep 17 00:00:00 2001
From: Imbris <imbrisf@gmail.com>
Date: Thu, 24 Oct 2019 20:02:29 -0400
Subject: [PATCH] improvement: roughly ~20% speedup of terrain meshing by
 eliminating redundant lookups of terrain blocks

---
 voxygen/src/mesh/segment.rs | 34 ++++++++++++++-----
 voxygen/src/mesh/terrain.rs | 67 ++++++++++++++++++++++++-------------
 voxygen/src/mesh/vol.rs     | 45 +++++--------------------
 3 files changed, 78 insertions(+), 68 deletions(-)

diff --git a/voxygen/src/mesh/segment.rs b/voxygen/src/mesh/segment.rs
index a588c33b3d..32094fd0f9 100644
--- a/voxygen/src/mesh/segment.rs
+++ b/voxygen/src/mesh/segment.rs
@@ -27,8 +27,7 @@ impl Meshable<FigurePipeline, FigurePipeline> for Segment {
             if let Some(col) = vox.get_color() {
                 vol::push_vox_verts(
                     &mut mesh,
-                    self,
-                    pos,
+                    faces_to_make(self, pos, true, |vox| vox.is_empty()),
                     offs + pos.map(|e| e as f32),
                     &[[[Rgba::from_opaque(col); 3]; 3]; 3],
                     |origin, norm, col, ao, light| {
@@ -39,7 +38,6 @@ impl Meshable<FigurePipeline, FigurePipeline> for Segment {
                             0,
                         )
                     },
-                    true,
                     &{
                         let mut ls = [[[0.0; 3]; 3]; 3];
                         for x in 0..3 {
@@ -59,7 +57,6 @@ impl Meshable<FigurePipeline, FigurePipeline> for Segment {
                         }
                         ls
                     },
-                    |vox| vox.is_empty(),
                 );
             }
         }
@@ -83,8 +80,7 @@ impl Meshable<SpritePipeline, SpritePipeline> for Segment {
             if let Some(col) = vox.get_color() {
                 vol::push_vox_verts(
                     &mut mesh,
-                    self,
-                    pos,
+                    faces_to_make(self, pos, true, |vox| vox.is_empty()),
                     offs + pos.map(|e| e as f32),
                     &[[[Rgba::from_opaque(col); 3]; 3]; 3],
                     |origin, norm, col, ao, light| {
@@ -94,9 +90,7 @@ impl Meshable<SpritePipeline, SpritePipeline> for Segment {
                             linear_to_srgb(srgb_to_linear(col) * ao * light),
                         )
                     },
-                    true,
                     &[[[1.0; 3]; 3]; 3],
-                    |vox| vox.is_empty(),
                 );
             }
         }
@@ -104,3 +98,27 @@ impl Meshable<SpritePipeline, SpritePipeline> for Segment {
         (mesh, Mesh::new())
     }
 }
+
+/// Use the 6 voxels/blocks surrounding the one at the specified position
+/// to detemine which faces should be drawn
+fn faces_to_make<V: ReadVol>(
+    seg: &V,
+    pos: Vec3<i32>,
+    error_makes_face: bool,
+    should_add: impl Fn(&V::Vox) -> bool,
+) -> [bool; 6] {
+    let (x, y, z) = (Vec3::unit_x(), Vec3::unit_y(), Vec3::unit_z());
+    let make_face = |offset| {
+        seg.get(pos + offset)
+            .map(|v| should_add(v))
+            .unwrap_or(error_makes_face)
+    };
+    [
+        make_face(-x),
+        make_face(x),
+        make_face(-y),
+        make_face(y),
+        make_face(-z),
+        make_face(z),
+    ]
+}
diff --git a/voxygen/src/mesh/terrain.rs b/voxygen/src/mesh/terrain.rs
index fec89fb225..fc557a5ffd 100644
--- a/voxygen/src/mesh/terrain.rs
+++ b/voxygen/src/mesh/terrain.rs
@@ -180,19 +180,21 @@ impl<V: RectRasterableVol<Vox = Block> + ReadVol + Debug> Meshable<TerrainPipeli
                         .unwrap_or(Rgba::zero())
                 };
 
+                let mut blocks = [[[None; 3]; 3]; 3];
                 let mut colors = [[[Rgba::zero(); 3]; 3]; 3];
                 for i in 0..3 {
                     for j in 0..3 {
                         for k in 0..3 {
-                            colors[k][j][i] = get_color(
-                                vol_cached
-                                    .get(
-                                        Vec3::new(x, y, range.min.z)
-                                            + Vec3::new(i as i32, j as i32, k as i32)
-                                            - 1,
-                                    )
-                                    .ok(),
-                            );
+                            let block = vol_cached
+                                .get(
+                                    Vec3::new(x, y, range.min.z)
+                                        + Vec3::new(i as i32, j as i32, k as i32)
+                                        - 1,
+                                )
+                                .ok()
+                                .copied();
+                            colors[k][j][i] = get_color(block.as_ref());
+                            blocks[k][j][i] = block;
                         }
                     }
                 }
@@ -203,6 +205,8 @@ impl<V: RectRasterableVol<Vox = Block> + ReadVol + Debug> Meshable<TerrainPipeli
 
                     lights[0] = lights[1];
                     lights[1] = lights[2];
+                    blocks[0] = blocks[1];
+                    blocks[1] = blocks[2];
                     colors[0] = colors[1];
                     colors[1] = colors[2];
 
@@ -213,44 +217,39 @@ impl<V: RectRasterableVol<Vox = Block> + ReadVol + Debug> Meshable<TerrainPipeli
                     }
                     for i in 0..3 {
                         for j in 0..3 {
-                            colors[2][j][i] = get_color(
-                                vol_cached
-                                    .get(pos + Vec3::new(i as i32, j as i32, 2) - 1)
-                                    .ok(),
-                            );
+                            let block = vol_cached
+                                .get(pos + Vec3::new(i as i32, j as i32, 2) - 1)
+                                .ok()
+                                .copied();
+                            colors[2][j][i] = get_color(block.as_ref());
+                            blocks[2][j][i] = block;
                         }
                     }
 
-                    let block = vol_cached.get(pos).ok();
+                    let block = blocks[1][1][1];
 
                     // Create mesh polygons
                     if block.map(|vox| vox.is_opaque()).unwrap_or(false) {
                         vol::push_vox_verts(
                             &mut opaque_mesh,
-                            self,
-                            pos,
+                            faces_to_make(&blocks, false, |vox| !vox.is_opaque()),
                             offs,
                             &colors, //&[[[colors[1][1][1]; 3]; 3]; 3],
                             |pos, norm, col, ao, light| {
                                 TerrainVertex::new(pos, norm, col, light.min(ao))
                             },
-                            false,
                             &lights,
-                            |vox| !vox.is_opaque(),
                         );
                     } else if block.map(|vox| vox.is_fluid()).unwrap_or(false) {
                         vol::push_vox_verts(
                             &mut fluid_mesh,
-                            self,
-                            pos,
+                            faces_to_make(&blocks, false, |vox| vox.is_air()),
                             offs,
                             &colors,
                             |pos, norm, col, _ao, light| {
                                 FluidVertex::new(pos, norm, col, light, 0.3)
                             },
-                            false,
                             &lights,
-                            |vox| vox.is_air(),
                         );
                     }
                 }
@@ -261,6 +260,28 @@ impl<V: RectRasterableVol<Vox = Block> + ReadVol + Debug> Meshable<TerrainPipeli
     }
 }
 
+/// Use the 6 voxels/blocks surrounding the center
+/// to detemine which faces should be drawn
+/// Unlike the one in segments.rs this uses a provided array of blocks instead
+/// of retrieving from a volume
+/// blocks[z][y][x]
+fn faces_to_make(
+    blocks: &[[[Option<Block>; 3]; 3]; 3],
+    error_makes_face: bool,
+    should_add: impl Fn(Block) -> bool,
+) -> [bool; 6] {
+    // Faces to draw
+    let make_face = |opt_v: Option<Block>| opt_v.map(|v| should_add(v)).unwrap_or(error_makes_face);
+    [
+        make_face(blocks[1][1][0]),
+        make_face(blocks[1][1][2]),
+        make_face(blocks[1][0][1]),
+        make_face(blocks[1][2][1]),
+        make_face(blocks[0][1][1]),
+        make_face(blocks[2][1][1]),
+    ]
+}
+
 /*
 impl<V: BaseVol<Vox = Block> + ReadVol + Debug> Meshable for VolGrid3d<V> {
     type Pipeline = TerrainPipeline;
diff --git a/voxygen/src/mesh/vol.rs b/voxygen/src/mesh/vol.rs
index 8b342661c3..04014b3b28 100644
--- a/voxygen/src/mesh/vol.rs
+++ b/voxygen/src/mesh/vol.rs
@@ -1,7 +1,5 @@
 use vek::*;
 
-use common::vol::ReadVol;
-
 use crate::render::{
     mesh::{Mesh, Quad},
     Pipeline,
@@ -151,25 +149,18 @@ fn create_quad<P: Pipeline, F: Fn(Vec3<f32>, Vec3<f32>, Rgb<f32>, f32, f32) -> P
     }
 }
 
-pub fn push_vox_verts<V: ReadVol, P: Pipeline>(
+pub fn push_vox_verts<P: Pipeline>(
     mesh: &mut Mesh<P>,
-    vol: &V,
-    pos: Vec3<i32>,
+    faces: [bool; 6],
     offs: Vec3<f32>,
     cols: &[[[Rgba<u8>; 3]; 3]; 3],
     vcons: impl Fn(Vec3<f32>, Vec3<f32>, Rgb<f32>, f32, f32) -> P::Vertex,
-    error_makes_face: bool,
     darknesses: &[[[f32; 3]; 3]; 3],
-    should_add: impl Fn(&V::Vox) -> bool,
 ) {
     let (x, y, z) = (Vec3::unit_x(), Vec3::unit_y(), Vec3::unit_z());
 
     // -x
-    if vol
-        .get(pos - Vec3::unit_x())
-        .map(|v| should_add(v))
-        .unwrap_or(error_makes_face)
-    {
+    if faces[0] {
         mesh.push_quad(create_quad(
             offs,
             Vec3::unit_z(),
@@ -181,11 +172,7 @@ pub fn push_vox_verts<V: ReadVol, P: Pipeline>(
         ));
     }
     // +x
-    if vol
-        .get(pos + Vec3::unit_x())
-        .map(|v| should_add(v))
-        .unwrap_or(error_makes_face)
-    {
+    if faces[1] {
         mesh.push_quad(create_quad(
             offs + Vec3::unit_x(),
             Vec3::unit_y(),
@@ -197,11 +184,7 @@ pub fn push_vox_verts<V: ReadVol, P: Pipeline>(
         ));
     }
     // -y
-    if vol
-        .get(pos - Vec3::unit_y())
-        .map(|v| should_add(v))
-        .unwrap_or(error_makes_face)
-    {
+    if faces[2] {
         mesh.push_quad(create_quad(
             offs,
             Vec3::unit_x(),
@@ -213,11 +196,7 @@ pub fn push_vox_verts<V: ReadVol, P: Pipeline>(
         ));
     }
     // +y
-    if vol
-        .get(pos + Vec3::unit_y())
-        .map(|v| should_add(v))
-        .unwrap_or(error_makes_face)
-    {
+    if faces[3] {
         mesh.push_quad(create_quad(
             offs + Vec3::unit_y(),
             Vec3::unit_z(),
@@ -229,11 +208,7 @@ pub fn push_vox_verts<V: ReadVol, P: Pipeline>(
         ));
     }
     // -z
-    if vol
-        .get(pos - Vec3::unit_z())
-        .map(|v| should_add(v))
-        .unwrap_or(error_makes_face)
-    {
+    if faces[4] {
         mesh.push_quad(create_quad(
             offs,
             Vec3::unit_y(),
@@ -245,11 +220,7 @@ pub fn push_vox_verts<V: ReadVol, P: Pipeline>(
         ));
     }
     // +z
-    if vol
-        .get(pos + Vec3::unit_z())
-        .map(|v| should_add(v))
-        .unwrap_or(error_makes_face)
-    {
+    if faces[5] {
         mesh.push_quad(create_quad(
             offs + Vec3::unit_z(),
             Vec3::unit_x(),