wgsl for loop syntax

Question

i found the following example on https://www.w3.org/TR/WGSL/#for-statement

for(var i: i32 = 0; i < 4; i++) {
  if a == 0 {
    continue;
  }
  a = a + 2;
}

but my code doesn't work

// shader.wgsl
struct MarchOutput {
    steps: i32;
    depth: f32;
    minimum_distance: f32;
    hit: bool;
};

fn march(
    point: vec3<f32>, direction: vec3<f32>,
    max_steps: i32, max_shading_distance: f32, min_hit_distance: f32
) -> MarchOutput {
    var out = MarchOutput ( 0, 0.0, max_shading_distance, false );

    for (out.steps=0; out.depth < max_shading_distance && out.steps < max_steps; out.steps++) {
        var current_position: vec3<f32> = point + direction * depth;
        var current_distance: f32 = SDF(current_position);

        if (abs(current_distance) < min_hit_distance) {
            out.hit = true;
            break;
        }

        out.minimum_distance = min(out.minimum_distance, current_distance);
        out.depth += current_distance;
    }

    return out;
}

error:

Shader 'shader' parsing error: expected operation ('='), found '+'

┌─ wgsl:95:88

95 │ for (out.steps=0; out.depth < max_shading_distance && out.steps < max_steps; out.steps++) {

expected operation ('='), found '+'

what am i doing wrong here ?

Answer 1

the latest released version does not has the increment and decrement operators or the += (and other similar operators). However, the naga master branch has the commits merged so in future releases these operators will work. For now use i=i+1