message: Patch checkerboard.frag for GLES compat (input/output precise match)
diff: * THE SOFTWARE.
  ******************************************************************************/
  +// for GLES compatibility where we must match blit.vert
  +layout (location = 0) in vec2 uv;
  +
  layout (location = 0) out vec4 color_out;
  layout (binding = 0, std140) uniform checkeruniforms
  