feat(extensions): PathStyleExtension save 1 instance vertex when highPrecisionDash is not used (#10008)

Author: amarant

modules/extensions/src/path-style/path-style-extension.ts

@@ -4,9 +4,9 @@
 
 import {LayerExtension, _mergeShaders as mergeShaders} from '@deck.gl/core';
 import {vec3} from '@math.gl/core';
-import {dashShaders, offsetShaders} from './shaders.glsl';
+import {dashShaders, Defines, offsetShaders} from './shaders.glsl';
 
-import type {Layer, LayerContext, Accessor, UpdateParameters} from '@deck.gl/core';
+import type {Accessor, Layer, LayerContext, UpdateParameters} from '@deck.gl/core';
 import type {ShaderModule} from '@luma.gl/shadertools';
 
 const defaultProps = {
@@ -87,8 +87,12 @@ export default class PathStyleExtension extends LayerExtension<PathStyleExtensio
 
     // Merge shader injection
     let result = {} as {inject: Record<string, string>};
+    const defines: Defines = {};
     if (extension.opts.dash) {
       result = mergeShaders(result, dashShaders);
+      if (extension.opts.highPrecisionDash) {
+        defines.HIGH_PRECISION_DASH = true;
+      }
     }
     if (extension.opts.offset) {
       result = mergeShaders(result, offsetShaders);
@@ -104,7 +108,8 @@ export default class PathStyleExtension extends LayerExtension<PathStyleExtensio
       }
     };
     return {
-      modules: [pathStyle]
+      modules: [pathStyle],
+      defines
     };
   }
 
@@ -118,19 +123,15 @@ export default class PathStyleExtension extends LayerExtension<PathStyleExtensio
     if (extension.opts.dash) {
       attributeManager.addInstanced({
         instanceDashArrays: {size: 2, accessor: 'getDashArray'},
-        instanceDashOffsets: extension.opts.highPrecisionDash
+        ...(extension.opts.highPrecisionDash
           ? {
-              size: 1,
-              accessor: 'getPath',
-              transform: extension.getDashOffsets.bind(this)
-            }
-          : {
-              size: 1,
-              update: attribute => {
-                attribute.constant = true;
-                attribute.value = [0];
+              instanceDashOffsets: {
+                size: 1,
+                accessor: 'getPath',
+                transform: extension.getDashOffsets.bind(this)
               }
             }
+          : {})
       });
     }
     if (extension.opts.offset) {

modules/extensions/src/path-style/shaders.glsl.ts

@@ -2,18 +2,32 @@
 // SPDX-License-Identifier: MIT
 // Copyright (c) vis.gl contributors
 
+export type Defines = {
+  // Defines passed externally
+  /**
+   * Enable high precision dash rendering.
+   */
+  HIGH_PRECISION_DASH?: boolean;
+};
+
 export const dashShaders = {
   inject: {
     'vs:#decl': `
 in vec2 instanceDashArrays;
+#ifdef HIGH_PRECISION_DASH
 in float instanceDashOffsets;
+#endif
 out vec2 vDashArray;
 out float vDashOffset;
 `,
 
     'vs:#main-end': `
 vDashArray = instanceDashArrays;
+#ifdef HIGH_PRECISION_DASH
 vDashOffset = instanceDashOffsets / width.x;
+#else
+vDashOffset = 0.0;
+#endif
 `,
 
     'fs:#decl': `