Support for captured variables? about gpu.js HOT 7 CLOSED

Global variables in the kernel? Every variable is already a global variable in the kernel.

Or do you mean captured variables? That would be tricky, but there should be no issues regarding performance.

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Oh sorry, i meant captured variables. E,g,

var a = 1;

function b() {
return a + 1;
}

gpu.makeKernel(
var main = func() {
a = a + 1;
b();
}
}

i capture a in both b and main. How?

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I can see how this can be implemented but I'm not sure if you're going to like what I'm going to say.

1. We can prefix all compiler functions and variables with "___" and reserve that namespace for ourselves. This is to protect the compiler from step 2.
2. When you reach a dangling variable like "a" inside the compiler, perform var x = eval("a;") inside the compiler to retrieve "a" from the environment and output the variable into the code. This goes the same for functions, gpu.addFunction( eval("myFunc") )...

The variable "a" is going to be a snapshot at the time of compilation and is readonly. Writeback is practically impossible in shaders as it is possible to only write to one texture target (the return value) unless you want to do multiple passes with recalculations.

Thoughts?

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I think the existing constants implementations workflow for GPU would make more sense?

Global modifiable variable as fuzz say is impossible however.

from gpu.js.

This is now handled via:

var kernel = gpu.createKernel(function() {
  return mySpecialNumber;
}, { constants: { mySpecialNumber: 100 } });

from gpu.js.

As it stands, there is no capture of variables.: functions need to be added manually, same as any global variables we want captured. Worse, to access a global variable one must use the "this.constants' prefix, so the function cannot be tested outside the kernel.
I think the bullet #2 in @fuzzie360 proposed is the most useful.
My use case is an Observable notebook where each parameter is defined by a cell.
When they are changed, the cells defining the kernels are re-run, and the new value would be captured.
The case against this is that changing it will make global variables captured once implicit (and harder to see).

2. When you reach a dangling variable like "a" inside the compiler, perform var x = eval("a;") inside the compiler to retrieve "a" from the environment and output the variable into the code. This goes the same for functions, gpu.addFunction( eval("myFunc") )...

from gpu.js.

Worse, to access a global variable one must use the "this.constants' prefix, so the function cannot be tested outside the kernel.

I can only reply with what was stated:

Global modifiable variable as fuzz say is impossible however.

Do you have a proof of concept that you'd like to propose?

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