SNOWFLOW: WebGPU Terrain Lab

// SNOWFLOW WebGPU WGSL Heightfield & Waterbending Compute Shader
struct TerrainNode {
  height : f32,
  snow_depth : f32,
  water_depth : f32,
  velocity : vec2<f32>,
};

@group(0) @binding(0) var<storage, read_write> terrainMap : array<TerrainNode>;
@group(0) @binding(1) var<uniform> params : SimParams;

struct SimParams {
  grid_res : u32,
  delta_time : f32,
  flow_rate : f32,
  viscosity : f32,
};

@compute @workgroup_size(16, 16)
fn mainCompute(@builtin(global_invocation_id) global_id : vec3<u32>) {
  let x = global_id.x;
  let z = global_id.y;
  if (x >= params.grid_res || z >= params.grid_res) { return; }

  let index = z * params.grid_res + x;
  var node = terrainMap[index];

  // Hydraulic Erosion & Snow Accumulation Integration Step
  if (node.water_depth > 0.001) {
    let dh_dx = terrainMap[index + 1].height - node.height;
    let dh_dz = terrainMap[index + params.grid_res].height - node.height;
    node.velocity += vec2<f32>(-dh_dx, -dh_dz) * params.flow_rate * params.delta_time;
    node.height -= length(node.velocity) * 0.02 * params.delta_time; // Sediment pick-up
  }

  // Thermal Erosion Slope Stabilization
  terrainMap[index] = node;
}