From 787011d16454ca686c1bdc30ad3d8e4d0f0031f8 Mon Sep 17 00:00:00 2001
From: MihailRis <mexaruc@gmail.com>
Date: Sun, 9 Feb 2025 14:48:53 +0300
Subject: [PATCH] optimize PrecipitationRenderer

---
 src/graphics/render/PrecipitationRenderer.cpp | 52 ++++++++++++------
 src/util/CentredMatrix.hpp                    | 55 +++++++++++++++++++
 2 files changed, 91 insertions(+), 16 deletions(-)
 create mode 100644 src/util/CentredMatrix.hpp

diff --git a/src/graphics/render/PrecipitationRenderer.cpp b/src/graphics/render/PrecipitationRenderer.cpp
index c54dd872..95297f83 100644
--- a/src/graphics/render/PrecipitationRenderer.cpp
+++ b/src/graphics/render/PrecipitationRenderer.cpp
@@ -7,7 +7,10 @@
 #include "graphics/core/Texture.hpp"
 #include "lighting/Lightmap.hpp"
 #include "maths/util.hpp"
+#include "maths/voxmaths.hpp"
+#include "util/CentredMatrix.hpp"
 #include "settings.hpp"
+#include "voxels/Chunk.hpp"
 #include "voxels/Chunks.hpp"
 #include "window/Camera.hpp"
 #include "world/Level.hpp"
@@ -29,12 +32,20 @@ PrecipitationRenderer::~PrecipitationRenderer() = default;
 
 int PrecipitationRenderer::getHeightAt(int x, int z) {
     int y = CHUNK_H - 1;
+    int cx = floordiv<CHUNK_W>(x);
+    int cz = floordiv<CHUNK_D>(z);
+    auto chunk = chunks.getChunk(cx, cz);
+    if (chunk == nullptr) {
+        return y;
+    }
+    y = chunk->top;
+    x -= cx * CHUNK_W;
+    z -= cz * CHUNK_D;
     while (y > 0) {
-        if (auto voxel = chunks.get({x, y, z})) {
-            if (voxel->id == 0) {
-                y--;
-                continue;
-            }
+        const auto& vox = chunk->voxels[vox_index(x, y, z)];
+        if (vox.id == 0) {
+            y--;
+            continue;
         }
         break;
     }
@@ -68,12 +79,12 @@ void PrecipitationRenderer::render(const Camera& camera, float delta) {
     const auto& front = camera.front;
     glm::ivec2 size {1, 16};
 
-    float horizontal = 0.5f;
+    float horizontal = 0.5f * 5;
 
     glm::vec4 light = light_at(chunks, x, y, z);
 
-    int radius = 6;
-    int depth = 12;
+    const int radius = 6;
+    const int depth = 12;
     float scale = 0.4f;
     int quads = 0;
     float k = 21.41149;
@@ -88,16 +99,26 @@ void PrecipitationRenderer::render(const Camera& camera, float delta) {
         {{0, 0, 1}, {1, 0, 0}},
     };
 
+    util::CentredMatrix<int, (depth + 1) * 2> heights;
+    heights.setCenter(x, z);
+    for (int z = heights.beginY(); z < heights.endY(); z++) {
+        for (int x = heights.beginX(); x < heights.endX(); x++) {
+            heights.at(x, z) = getHeightAt(x, z);
+        }
+    }
+
     for (const auto& face : faces) {
         for (int lx = -radius; lx <= radius; lx++) {
             for (int lz = depth; lz > 0; lz--) {
+                // Position calculations
                 glm::vec3 pos = face.right * static_cast<float>(lx) +
                                 face.front * static_cast<float>(lz);
                 pos += glm::vec3(x, 0, z);
-                pos.y = glm::max(y - size.y / 2, getHeightAt(pos.x, pos.z)) +
+                pos.y = glm::max(y - size.y / 2, heights.at(pos.x, pos.z)) +
                         size.y / 2 + 1;
                 pos += glm::vec3(0.5f, 0.0f, 0.5f);
                 
+                // UV coords calculations
                 float m = glm::sign(face.right.x + face.right.z);
                 int ux = pos.x;
                 int uz = pos.z;
@@ -106,9 +127,13 @@ void PrecipitationRenderer::render(const Camera& camera, float delta) {
                     std::swap(ux, uz);
                 }
 
-                glm::vec4 light = light_at(chunks, pos.x, y, pos.z);
                 random.setSeed(uz);
                 float hspeed = (random.randFloat() * 2.0f - 1.0f) * horizontal;
+                float u1 = ux * scale + timer * hspeed * -m;
+                float v1 = timer + pos.y * scale + uz * k;
+
+                // Draw
+                glm::vec4 light = light_at(chunks, pos.x, y, pos.z);
                 batch->quad(
                     pos,
                     face.right,
@@ -116,12 +141,7 @@ void PrecipitationRenderer::render(const Camera& camera, float delta) {
                     size,
                     light,
                     glm::vec3(1.0f),
-                    UVRegion(
-                        ux * scale + timer * hspeed * -m,
-                        timer + pos.y * scale + uz * k,
-                        (ux + m) * scale + timer * hspeed * -m,
-                        timer + (size.y + pos.y) * scale + uz * k
-                    )
+                    UVRegion(u1, v1, u1 + m * scale, v1 + size.y * scale)
                 );
             }
         }
diff --git a/src/util/CentredMatrix.hpp b/src/util/CentredMatrix.hpp
new file mode 100644
index 00000000..805a1aa1
--- /dev/null
+++ b/src/util/CentredMatrix.hpp
@@ -0,0 +1,55 @@
+#pragma once
+
+#include <array>
+#include <stdexcept>
+
+namespace util {
+    template<typename T, int diameter, typename CoordT = int>
+    class CentredMatrix {
+    public:
+        static constexpr CoordT radius = diameter / 2;
+
+        CentredMatrix() {}
+
+        void setCenter(CoordT x, CoordT y) {
+            centerX = x;
+            centerY = y;
+        }
+
+        T& at(CoordT x, CoordT y) {
+            x -= centerX - (diameter - radius);
+            y -= centerY - (diameter - radius);
+            if (x < 0 || y < 0 || x >= diameter || y >= diameter) {
+                throw std::invalid_argument("position is out if matrix");
+            }
+            return arr.at(y * diameter + x);
+        }
+
+        auto begin() {
+            return arr.begin();
+        }
+
+        auto end() {
+            return arr.end();
+        }
+
+        CoordT beginX() const {
+            return centerX - (diameter - radius);
+        }
+
+        CoordT beginY() const {
+            return centerY - (diameter - radius);
+        }
+
+        CoordT endX() const {
+            return centerX + radius;
+        }
+        
+        CoordT endY() const {
+            return centerY + radius;
+        }
+    private:
+        std::array<T, diameter * diameter> arr;
+        CoordT centerX = 0, centerY = 0;
+    };
+}