[le-foot]

I downloaded the Apple GLEssentials sample code and tried to get Metal to run, but received this error:

[***MetalGL ERROR***] GL_INVALID_VALUE. glLinkProgram(): Shader 1 does not exist
/SourceCache/AcceleratorKit/AcceleratorKit-17.7/Framework/MTLRenderPipeline.mm:839: failed assertion vertexFunction must not be nil.'

I was wondering what this means, and how can I go about fixing it?

[Bill Hollings]

@le-foot

Thanks for bringing this to our attention. It looks like you’ve uncovered an issue with how MetalGL handles the deletion of a shader that has just been attached to a program.

We’ll fix this for the next release. In the meantime, you can work around the issue in GLEssentials by commenting out the calls to glDeleteShader() in OpenGLRender.m.

…Bill

[le-foot]

Hi Bill,

I commented glDeleteShader() out, but got the following error:

/BuildRoot/Library/Caches/com.apple.xbs/Sources/Metal/Metal-54.30/Framework/MTLRenderPipeline.mm:1061: failed assertion 'No valid pixelFormats set.'

[Bill Hollings]

@le-foot

Are you running this on a device with iOS 9? If so, there is a known issue with a change to the Metal API on iOS 9 that causes the pixel format error.

This is fixed in the MetalGL release that is due out at the end of this week.

In the meantime, do you have a device running iOS 8 that you can test with?

…Bill

[le-foot]

Hi Bill,

I do have an iOS 8 device, and I still couldn’t get it to work. I have the following error when running Apple’s sample code:

[***MetalGL ERROR***] GL_INVALID_OPERATION. glGetUniformLocation(): Shader program 0 has not been linked.
2015-09-16 12:39:39.095 GLEssentials[1639:916118] No modelViewProjectionMatrix in character shader
2015-09-16 12:39:39.096 GLEssentials[1639:916118] GLError GL_INVALID_OPERATION set in File:/Users/macuser/Downloads/GLEssentials/GLEssentials/Source/Classes/OpenGLRenderer.m Line:436
2015-09-16 12:39:39.108 GLEssentials[1639:916118] Vtx Shader compile log:The OpenGL GLSL shader source code could not be converted to Metal shader source code because the MetalGL Shader Converter has not been linked to this build.

Shader source was not provided.

[Bill Hollings]

The latest release of MetalGL is out, and includes a fix for the iOS 9 issue mentioned above.

MetalGL 0.10.0 can be downloaded here.

…Bill

[Bill Hollings]

@le-foot

As the error message indicated, it looks like you have not linked your app to the MetalGL Shader Converter.

The installation section of the README.md (or now README-UserGuide.md) document in the MetalGL package includes instructions for how to do that.

…Bill

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