Function prepare_tiles 

fn prepare_tiles(
    prim_instance_index: PrimitiveInstanceIndex,
    local_rect: &LayoutRect,
    local_clip_rect: &LayoutRect,
    device_clip_rect: &DeviceRect,
    pattern: &Pattern,
    quad_flags: QuadFlags,
    aa_flags: EdgeMask,
    clip_chain: &ClipChainInstance,
    gpu_transform: GpuTransformId,
    transform: &mut QuadTransformState,
    pic_context: &PictureContext,
    ctx: &PatternBuilderContext<'_>,
    interned_clips: &DataStore<ClipIntern>,
    frame_state: &mut FrameBuildingState<'_>,
    scratch: &mut PrimitiveScratchBuffer,
    targets: &[CommandBufferIndex],
)