don't use fences for now, too slow

src/mol-gl/webgl/context.ts

@@ -79,18 +79,23 @@ let SentWebglSyncObjectNotSupportedInWebglMessage = false
 function waitForGpuCommandsComplete(gl: GLRenderingContext): Promise<void> {
     return new Promise(resolve => {
         if (isWebGL2(gl)) {
+            // TODO seems quite slow
             fence(gl, resolve)
         } else {
             if (!SentWebglSyncObjectNotSupportedInWebglMessage) {
                 console.info('Sync object not supported in WebGL')
                 SentWebglSyncObjectNotSupportedInWebglMessage = true
             }
-            gl.readPixels(0, 0, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, tmpPixel)
+            waitForGpuCommandsCompleteSync(gl)
             resolve()
         }
     })
 }
 
+function waitForGpuCommandsCompleteSync(gl: GLRenderingContext): void {
+    gl.readPixels(0, 0, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, tmpPixel)
+}
+
 export function createImageData(buffer: ArrayLike<number>, width: number, height: number) {
     const w = width * 4
     const h = height
@@ -147,6 +152,7 @@ export interface WebGLContext {
     readPixels: (x: number, y: number, width: number, height: number, buffer: Uint8Array) => void
     readPixelsAsync: (x: number, y: number, width: number, height: number, buffer: Uint8Array) => Promise<void>
     waitForGpuCommandsComplete: () => Promise<void>
+    waitForGpuCommandsCompleteSync: () => void
     destroy: () => void
 }
 
@@ -279,6 +285,7 @@ export function createContext(gl: GLRenderingContext): WebGLContext {
         },
         readPixelsAsync,
         waitForGpuCommandsComplete: () => waitForGpuCommandsComplete(gl),
+        waitForGpuCommandsCompleteSync: () => waitForGpuCommandsCompleteSync(gl),
 
         destroy: () => {
             unbindResources(gl)

src/mol-math/geometry/gaussian-density/gpu.ts

@@ -110,7 +110,7 @@ async function GaussianDensityTexture2d(ctx: RuntimeContext, webgl: WebGLContext
     render(texture)
 
     if (ctx.shouldUpdate) await ctx.update({ message: 'gpu gaussian density calculation' })
-    await webgl.waitForGpuCommandsComplete()
+    await webgl.waitForGpuCommandsCompleteSync()
 
     return { texture, scale: Vec3.inverse(Vec3.zero(), delta), bbox: expandedBox, dim }
 }
@@ -157,7 +157,7 @@ async function GaussianDensityTexture3d(ctx: RuntimeContext, webgl: WebGLContext
     render(texture)
 
     await ctx.update({ message: 'gpu gaussian density calculation' });
-    await webgl.waitForGpuCommandsComplete()
+    await webgl.waitForGpuCommandsCompleteSync()
 
     return { texture, scale: Vec3.inverse(Vec3.zero(), delta), bbox: expandedBox, dim }
 }