Fragment Shader does not work if not using uniform

[dezmou]

Hello,

I try to fool around with the game of Life playground.

If we take this piece of code

let render = ti.kernel(() => {
  ti.clearColor(renderTarget, [0.0, 0.0, 0.0, 1.0]);
  for (let v of ti.inputVertices(vertices)) {
    ti.outputPosition([v.x, v.y, 0.0, 1.0]);
    ti.outputVertex(v);
  }
  for (let f of ti.inputFragments()) {
    let coord = (f + 1) / 2.0;
    let cellIndex = ti.i32(coord * (liveness.dimensions - 1));
    let live = ti.f32(liveness[cellIndex]);
    ti.outputColor(renderTarget, [live, live, live, 1.0]);
  }
});

And let's say I don't want game of life but I want to fill the canvas with red pixel.

let render = ti.kernel(() => {
  ti.clearColor(renderTarget, [0.0, 0.0, 0.0, 1.0]);
  for (let v of ti.inputVertices(vertices)) {
    ti.outputPosition([v.x, v.y, 0.0, 1.0]);
    ti.outputVertex(v);
  }
  for (let f of ti.inputFragments()) {
    // let coord = (f + 1) / 2.0;
    // let cellIndex = ti.i32(coord * (liveness.dimensions - 1));
    // let live = ti.f32(liveness[cellIndex]);
    ti.outputColor(renderTarget, [1.0, 0.0, 0.0, 1.0]);
  }
});

I get black canvas and in the console :

Bind group layout index (0) doesn't correspond to a bind group for this pipeline.
 - While Validating GetBindGroupLayout (0) on [RenderPipeline]

If i uncomment the lines and keep my red pixel, then it work

let render = ti.kernel(() => {
  ti.clearColor(renderTarget, [0.0, 0.0, 0.0, 1.0]);
  for (let v of ti.inputVertices(vertices)) {
    ti.outputPosition([v.x, v.y, 0.0, 1.0]);
    ti.outputVertex(v);
  }
  for (let f of ti.inputFragments()) {
    let coord = (f + 1) / 2.0;
    let cellIndex = ti.i32(coord * (liveness.dimensions - 1));
    let live = ti.f32(liveness[cellIndex]);
    ti.outputColor(renderTarget, [1.0, 0.0, 0.0, 1.0]);
  }
});

I've also attempted with removing the lines instead of commenting it.

[dezmou]

Look like it work only if we are "using" some uniform even if we are not using it :
Those are two example that work :

for (let f of ti.inputFragments()) {
  let foo = liveness[[0, 0]];
  ti.outputColor(renderTarget, [1.0, 0.0, 0.0, 1.0]);
}

for (let f of ti.inputFragments()) {
  let foo = numNeighbors[[0, 0]];
  ti.outputColor(renderTarget, [1.0, 0.0, 0.0, 1.0]);
}

So maybe that is a niche bug that occure only when we want a fragment shader that does not use uniforms.