Bytes are being bound at index 0 to a shader argument with write access enabled.

Question

BartW OP

Created Aug ’20

Replies 2

Boosts 0

Views 1.3k

Participants 3

Hi all,

I don't understand the error:

validateFunctionArguments:3487: failed assertion `Fragment Function(MyFunction): Bytes are being bound at index 0 to a shader argument with write access enabled.

Does this error pertain to textures or to buffers?

What am I doing wrong:

Code Block     // set input texture
[commandEncoder setFragmentTexture:srcTexture
                           atIndex:0];
// set params
[commandEncoder setFragmentBytes:&params
                          length:sizeof(params)
                         atIndex:0];
[commandEncoder drawPrimitives:MTLPrimitiveTypeTriangleStrip
                       vertexStart:0
                       vertexCount:4];

The shader function header looks like this:

Code Block fragment float4 MyFunction(RasterizerData in [[ stage_in ]], device MyParams& params [[ buffer (0) ]], texture2d<half, access::sample> src [[ texture(0) ]])

MyParams is a struct of several floats and simd_float4 (because it seems that I can't use metal's float4 in a C++/Objective-C file. Texture has RenderTarget, ShaderRead and ShaderWrite usage.

Note, that this code seems to have worked in another project, but here it throws this error.

Any help appreciated.

Boost

Answer 1

Ceylo OP

Sep ’20

Blind guess but maybe missing a const in

Code Block device MyParams& params [[ buffer (0) ]]

?

0

Answer 2

mfalaleev OP

Apr ’21

you need to used a "constant" address space, not a "device"

Code Block fragment float4 MyFunction(
                           RasterizerData in [[ stage_in ]],
                           constant MyParams& params [[ buffer (0) ]],
                           texture2d<half, access::sample> src [[ texture(0) ]]
                          )

1