Merge pull request #8301 from processing/strands-cleanup

Makes sure p5.strands cleans up after an error

Author: ksen0

src/strands/p5.strands.js

@@ -65,39 +65,41 @@ function strands(p5, fn) {
 
   p5.Shader.prototype.modify = function(shaderModifier, scope = {}) {
     if (shaderModifier instanceof Function) {
-      // Reset the context object every time modify is called;
-      // const backend = glslBackend;
-      initStrandsContext(strandsContext, glslBackend, { active: true });
-      createShaderHooksFunctions(strandsContext, fn, this);
-      // TODO: expose this, is internal for debugging for now.
-      const options = { parser: true, srcLocations: false };
+      try {
+        // Reset the context object every time modify is called;
+        // const backend = glslBackend;
+        initStrandsContext(strandsContext, glslBackend, { active: true });
+        createShaderHooksFunctions(strandsContext, fn, this);
+        // TODO: expose this, is internal for debugging for now.
+        const options = { parser: true, srcLocations: false };
 
-      // 1. Transpile from strands DSL to JS
-      let strandsCallback;
-      if (options.parser) {
-        // #7955 Wrap function declaration code in brackets so anonymous functions are not top level statements, which causes an error in acorn when parsing
-        // https://github.com/acornjs/acorn/issues/1385
-        const sourceString = `(${shaderModifier.toString()})`;
-        strandsCallback = transpileStrandsToJS(p5, sourceString, options.srcLocations, scope);
-      } else {
-        strandsCallback = shaderModifier;
-      }
-
-      // 2. Build the IR from JavaScript API
-      const globalScope = createBasicBlock(strandsContext.cfg, BlockType.GLOBAL);
-      pushBlock(strandsContext.cfg, globalScope);
-      strandsCallback();
-      popBlock(strandsContext.cfg);
+        // 1. Transpile from strands DSL to JS
+        let strandsCallback;
+        if (options.parser) {
+          // #7955 Wrap function declaration code in brackets so anonymous functions are not top level statements, which causes an error in acorn when parsing
+          // https://github.com/acornjs/acorn/issues/1385
+          const sourceString = `(${shaderModifier.toString()})`;
+          strandsCallback = transpileStrandsToJS(p5, sourceString, options.srcLocations, scope);
+        } else {
+          strandsCallback = shaderModifier;
+        }
 
-      // 3. Generate shader code hooks object from the IR
-      // .......
-      const hooksObject = generateShaderCode(strandsContext);
+        // 2. Build the IR from JavaScript API
+        const globalScope = createBasicBlock(strandsContext.cfg, BlockType.GLOBAL);
+        pushBlock(strandsContext.cfg, globalScope);
+        strandsCallback();
+        popBlock(strandsContext.cfg);
 
-      // Reset the strands runtime context
-      deinitStrandsContext(strandsContext);
+        // 3. Generate shader code hooks object from the IR
+        // .......
+        const hooksObject = generateShaderCode(strandsContext);
 
-      // Call modify with the generated hooks object
-      return oldModify.call(this, hooksObject);
+        // Call modify with the generated hooks object
+        return oldModify.call(this, hooksObject);
+      } finally {
+        // Reset the strands runtime context
+        deinitStrandsContext(strandsContext);
+      }
     }
     else {
       return oldModify.call(this, shaderModifier)

test/unit/visual/cases/webgl.js

@@ -692,7 +692,7 @@ visualSuite('WebGL', function() {
     });
   });
 
-  visualSuite('textures in p5.strands', async () => {
+  visualSuite('textures in p5.strands', () => {
     visualTest('uniformTexture() works', async (p5, screenshot) => {
       p5.createCanvas(50, 50, p5.WEBGL);
       const tex = await p5.loadImage('/unit/assets/cat.jpg');
@@ -708,4 +708,18 @@ visualSuite('WebGL', function() {
       screenshot();
     });
   });
+
+  visualSuite('p5.strands', () => {
+    visualTest('it recovers from p5.strands errors', (p5, screenshot) => {
+      p5.createCanvas(50, 50, p5.WEBGL);
+      try {
+        p5.baseMaterialShader().modify(() => {
+          undefined.someMethod(); // This will throw an error
+        });
+      } catch (e) {}
+      p5.background('red');
+      p5.circle(p5.noise(0), p5.noise(0), 20);
+      screenshot();
+    });
+  });
 });

test/unit/visual/screenshots/WebGL/p5.strands/it recovers from p5.strands errors/000.png

@@ -0,0 +1,3 @@
+{
+  "numScreenshots": 1
+}