outsource async fetching

www/js/main.js

@@ -2,18 +2,31 @@ import { Smc } from "./smc/smc.js"
 
 main();
 
+async function fetchShader(uri, delegate) {
+  const res = await fetch(uri);
+  if (res.ok)
+    return await res.text();
+  this.raiseError(
+    SmcErr.FETCH_SHADER,
+    `Failed to load shader source ${url}: ${res.status} ${res.json()}`);
+  return ""
+}
+
+
 function main() {
   const canvas = document.querySelector("#gl-canvas");
   canvas.setAttribute('width', window.innerWidth);
   canvas.setAttribute('height', window.innerHeight);
 
-  new Smc(canvas)
-    .setMaxFps(30)
-    .setProgram(builder =>
-      builder
-      // .fetchVertexShader("../shaders/segfault.glsl")
-      // .fetchFragmentShader("../shaders/segfault.glsl"))
-    )
-    .run();
+
+  fetchShader("../shaders/segfault.glsl")
+    .then(frag =>
+      new Smc(canvas)
+        .setMaxFps(30)
+        .setProgram(builder =>
+          builder
+            .addFragmentShader(frag))
+        .run()
+    );
 }
 

www/js/smc/progbuilder.js

@@ -71,19 +71,21 @@ class SmcProgramBuilder {
         source
       )
     )
+    console.log(source)
     this.#hasFragmentShader = true;
     return this;
   }
 
-  fetchVertexShader(uri) {
-    this.#fetchShader(uri, (source) => this.addVertexShader(source));
-    return this;
-  }
+  // fetchVertexShader(uri) {
+  //   (async () => this.#fetchShader(uri, (source) => this.addVertexShader(source)))();
+  //   return this;
+  // }
 
-  fetchFragmentShader(uri) {
-    this.#fetchShader(uri, (source) => this.addFragmentShader(source));
-    return this;
-  }
+  // async fetchFragmentShader(uri) {
+  //   var delegate = (source) => this.addFragmentShader(source);
+  //   var source = await this.#fetchShader(uri);
+  //   return this;
+  // }
 
   build() {
     // avoid user accidental calls to build()
@@ -117,18 +119,15 @@ class SmcProgramBuilder {
     return shader;
   }
 
-  #fetchShader(uri, delegate) {
-    return fetch(uri)
-      .then(res => {
-        if (res.ok)
-          delegate(res.text());
-        else {
-          this.raiseError(
-            SmcErr.FETCH_SHADER,
-            `Failed to load shader source ${url}: ${res.status} ${res.json()}`);
-        }
-      });
-  }
+  // async #fetchShader(uri, delegate) {
+  //   const res = await fetch(uri);
+  //   if (res.ok)
+  //     return await res.text();
+  //   this.raiseError(
+  //     SmcErr.FETCH_SHADER,
+  //     `Failed to load shader source ${url}: ${res.status} ${res.json()}`);
+  //   return ""
+  // }
 
 }
 

www/js/smc/smc.js

@@ -127,9 +127,9 @@ class Smc {
 
   setProgram(delegate) {
     const builder = new SmcProgramBuilder(this.#gl, this.raiseError);
-    delegate(builder); // i pray js passes by ref well...
+    var result = delegate(builder);
 
-    this.#program = builder.build();
+    this.#program = result.build();
     if (!this.#gl.getProgramParameter(this.#program, this.#gl.LINK_STATUS)) {
       const infoLog = this.#gl.getProgramInfoLog(this.#program);
       this.raiseError(