Problem with iOS example VolumeRender

Dear All,

I compiled the VTK for iOS 12.4, and all the examples from Example/iOS/ works really well except the VolumeRender.

VTK/Examples/iOS/VolumeRender for iOS on iPhone XR didn’t show nothing only the background.

The first problem that I found was that the vtkVolumeShaderComposer.h from the VTK source code gave me an error, in this line:

float jitterValue = texture2D(in_noiseSampler, gl_FragCoord.xy / textureSize(in_noiseSampler, 0)).x; line because textureSize return ivec2 and the operator “/“ can not divide vec2 with ivec2

I fixed to:

ivec2 t_size = textureSize(in_noiseSampler, 0);

if(t_size.x == 0 || t_size.y == 0)


t_size = ivec2(1,1);


vec2 value = vec2(gl_FragCoord.x / float(t_size.x), gl_FragCoord.y / float(t_size.y));

float jitterValue = texture2D(in_noiseSampler, value).x;

Then the example ran without any problem but still the render didn’t show, only the color background.

Also, I enabled the OpenGL ES3, which is needed for this, as mentioned:

Any help on how to make this example works is really welcome.

Best regards,


I have the same problem as you. Do you solved it?