From d522c84aacdb176b64621cfca089dd6aed54d819 Mon Sep 17 00:00:00 2001
From: Andrew Prifer <2991360+AndrewPrifer@users.noreply.github.com>
Date: Fri, 4 Mar 2022 15:06:48 +0100
Subject: [PATCH] Create a proper infinite grid helper (#95)

---
 packages/r3f/src/InfiniteGridHelper/index.ts  | 141 ++++++++++++++++++
 .../r3f/src/components/SnapshotEditor.tsx     |   7 +-
 2 files changed, 146 insertions(+), 2 deletions(-)
 create mode 100644 packages/r3f/src/InfiniteGridHelper/index.ts

diff --git a/packages/r3f/src/InfiniteGridHelper/index.ts b/packages/r3f/src/InfiniteGridHelper/index.ts
new file mode 100644
index 0000000..6cb76ad
--- /dev/null
+++ b/packages/r3f/src/InfiniteGridHelper/index.ts
@@ -0,0 +1,141 @@
+// Inspired by https://github.com/Fyrestar/THREE.InfiniteGridHelper
+import {
+  Color,
+  DoubleSide,
+  GLSL3,
+  Mesh,
+  PlaneBufferGeometry,
+  ShaderMaterial,
+} from 'three'
+
+export class InfiniteGridHelper extends Mesh {
+  constructor({
+    divisions = 10,
+    scale = 0.1,
+    color = new Color('white'),
+    distance = 8000,
+    subgridOpacity = 0.05,
+    gridOpacity = 0.15,
+  } = {}) {
+    const geometry = new PlaneBufferGeometry(2, 2, 1, 1)
+
+    const material = new ShaderMaterial({
+      // Needs to be set so threejs doesn't mess things up in glsl3 code by trying to make glsl1 forward compatible
+      glslVersion: GLSL3,
+      side: DoubleSide,
+      uniforms: {
+        uScale: {
+          value: scale,
+        },
+        uDivisions: {
+          value: divisions,
+        },
+        uColor: {
+          value: color,
+        },
+        uDistance: {
+          value: distance,
+        },
+        uSubgridOpacity: {
+          value: subgridOpacity,
+        },
+        uGridOpacity: {
+          value: gridOpacity,
+        },
+      },
+      transparent: true,
+      // language=GLSL
+      vertexShader: `
+          out vec3 worldPosition;
+          uniform float uDistance;
+
+          void main() {
+              // Scale the plane by the drawing distance
+              worldPosition = position.xzy * uDistance;
+              worldPosition.xz += cameraPosition.xz;
+
+              gl_Position = projectionMatrix * modelViewMatrix * vec4(worldPosition, 1.0);
+          }
+      `,
+      // language=GLSL
+      fragmentShader: `
+          out vec4 fragColor;
+          in vec3 worldPosition;
+
+          uniform float uDivisions;
+          uniform float uScale;
+          uniform vec3 uColor;
+          uniform float uDistance;
+          uniform float uSubgridOpacity;
+          uniform float uGridOpacity;
+
+          float getGrid(float gapSize) {
+              vec2 worldPositionByDivision = worldPosition.xz / gapSize;
+
+              // Inverted, 0 where line, >1 where there's no line
+              // We use the worldPosition (which in this case we use similarly to UVs) differential to control the anti-aliasing
+              // We need to do the -0.5)-0.5 trick because the result fades out from 0 to 1, and we want both
+              // worldPositionByDivision == 0.3 and worldPositionByDivision == 0.7 to result in the same fade, i.e. 0.3,
+              // otherwise only one side of the line will be anti-aliased
+              vec2 grid = abs(fract(worldPositionByDivision-0.5)-0.5) / fwidth(worldPositionByDivision) / 2.0;
+              float gridLine = min(grid.x, grid.y);
+
+              // Uninvert and clamp
+              return 1.0 - min(gridLine, 1.0);
+          }
+
+          void main() {
+              float cameraDistanceToGridPlane = distance(cameraPosition.y, worldPosition.y);
+              float cameraDistanceToFragmentOnGridPlane = distance(cameraPosition.xz, worldPosition.xz);
+
+              // The size of the grid and subgrid are powers of each other and they are determined based on camera distance.
+              // The current grid will become the next subgrid when it becomes too small, and its next power becomes the new grid.
+              float subGridPower = pow(uDivisions, floor(log(cameraDistanceToGridPlane) / log(uDivisions)));
+              float gridPower = subGridPower * uDivisions;
+
+              // If we want to fade both the grid and its subgrid, we need to displays 3 different opacities, with the next grid being the third
+              float nextGridPower = gridPower * uDivisions;
+
+              // 1 where grid, 0 where no grid
+              float subgrid = getGrid(subGridPower * uScale);
+              float grid = getGrid(gridPower * uScale);
+              float nextGrid = getGrid(nextGridPower * uScale);
+
+              // Where we are between the introduction of the current grid power and when we switch to the next grid power
+              float stepPercentage = (cameraDistanceToGridPlane - subGridPower)/(gridPower - subGridPower);
+
+              // The last x percentage of the current step over which we want to fade
+              float fadeRange = 0.3;
+
+              // We calculate the fade percentage from the step percentage and the fade range
+              float fadePercentage = max(stepPercentage - 1.0 + fadeRange, 0.0) / fadeRange;
+
+              // Set base opacity based on how close we are to the drawing distance, with a cubic falloff
+              float baseOpacity = subgrid * pow(1.0 - min(cameraDistanceToFragmentOnGridPlane / uDistance, 1.0), 3.0);
+
+              // Shade the subgrid
+              fragColor = vec4(uColor.rgb, (baseOpacity - fadePercentage) * uSubgridOpacity);
+
+              // Somewhat arbitrary additional fade coefficient to counter anti-aliasing popping when switching between grid powers
+              float fadeCoefficient = 0.5;
+
+              // Shade the grid
+              fragColor.a = mix(fragColor.a, baseOpacity * uGridOpacity - fadePercentage * (uGridOpacity - uSubgridOpacity) * fadeCoefficient, grid);
+
+              // Shade the next grid
+              fragColor.a = mix(fragColor.a, baseOpacity * uGridOpacity, nextGrid);
+
+              if (fragColor.a <= 0.0) discard;
+          }
+      `,
+
+      extensions: {
+        derivatives: true,
+      },
+    })
+
+    super(geometry, material)
+
+    this.frustumCulled = false
+  }
+}
diff --git a/packages/r3f/src/components/SnapshotEditor.tsx b/packages/r3f/src/components/SnapshotEditor.tsx
index d18a482..02bb350 100644
--- a/packages/r3f/src/components/SnapshotEditor.tsx
+++ b/packages/r3f/src/components/SnapshotEditor.tsx
@@ -1,4 +1,4 @@
-import {useCallback, useLayoutEffect} from 'react'
+import {useCallback, useLayoutEffect, useMemo} from 'react'
 import React from 'react'
 import {Canvas} from '@react-three/fiber'
 import type {BaseSheetObjectType} from '../store'
@@ -14,6 +14,7 @@ import type {ISheet} from '@theatre/core'
 import useSnapshotEditorCamera from './useSnapshotEditorCamera'
 import {getEditorSheet, getEditorSheetObject} from './editorStuff'
 import type {$IntentionalAny} from '@theatre/shared/utils/types'
+import {InfiniteGridHelper} from '../InfiniteGridHelper'
 
 const GlobalStyle = createGlobalStyle`
   :host {
@@ -50,9 +51,11 @@ const EditorScene: React.FC<{snapshotEditorSheet: ISheet; paneId: string}> = ({
   const showGrid = useVal(editorObject?.props.viewport.showGrid) ?? true
   const showAxes = useVal(editorObject?.props.viewport.showAxes) ?? true
 
+  const grid = useMemo(() => new InfiniteGridHelper(), [])
+
   return (
     <>
-      {showGrid && <gridHelper args={[20, 20, '#6e6e6e', '#4a4b4b']} />}
+      {showGrid && <primitive object={grid} />}
       {showAxes && <axesHelper args={[500]} />}
       {editorCamera}