three.js does not auto-declare uniforms added via onBeforeCompile, so the
injected uMapRepeat/uMapOffset were undeclared and the card shader failed
to compile, rendering cards transparent. Prepend the declarations to the
vertex shader.
Move the card sprite repeat/offset out of per-card texture clones and
into a uniform injected into the material shader. Cards now share the
deck sheet (one GPU upload), the shader, and the geometry, with only
per-card material uniforms differing, so navigating a deck no longer
re-uploads the sheet on every step.
hypercross