typedef struct {
float4 v_Position [[position]];
float4 v_Color;
float2 v_TexCoord;
float2 v_PaperCoord;
} RasterizerData;
float4 apply_eraser(
float4 color,
float2 paper_coord,
metal::texture2d_ms<half> eraser_texture);
float4 apply_clip_mask(
float4 color,
float2 paper_coord,
metal::texture2d_ms<half> eraser_texture);