Failure to create opengl context in shader viewcontroller on iPhone 5 iOS 10

[awhill19]

Hi there,

I've just installed the app from the app store on my iphone and it is unable to create a GL context in the shader viewcontroller, leading to a "shader error" message. From a quick glance at the app code I'm guessing it may have something to do with the GL ES version. I'll dig around and try to find a fix.

[awhill19]

Yep, this is most likely the issue. OpenGL ES 3.0 hardware support started with iPhone 5s https://developer.apple.com/library/content/documentation/DeviceInformation/Reference/iOSDeviceCompatibility/HardwareGPUInformation/HardwareGPUInformation.html#//apple_ref/doc/uid/TP40013599-CH106-SW1

Is it possible to support ES 2.0 as a fallback, or is shadertoy dependent on 3.0? Many people are still using iphone 5 with the latest iOS version

[Ninja-Koala]

I think this is a duplicate of issue #14

[reindernijhoff]

Hi,

Yes you're right. I had to switch from OpenGL ES 2.0 to OpenGL ES 3.0. That's because OpenGL ES 3.0 has (almost) the same syntax as WebGL 2 which is the new WebGL version used on Shadertoy.

I will have a look if it's possible to make an OpenGL ES 2.0 fallback (and automatically rewrite the WebGL 2 shaders to a WebGL 1 syntax).