[Fix, Docs] (MG_Backend/DirectGLES): drain the attachment-format probe, and document the depth/stencil readback emulation switch

MobileGL/MG_Backend/DirectGLES/DirectGLES.cpp

@@ -6074,8 +6074,12 @@ namespace MobileGL::MG_Backend::DirectGLES {
 
             if (!isDefault) {
                 // A real object: ask it directly. That answer is certainly blit-compatible,
-                // so it is used on its own.
+                // so it is used on its own. The query binds the attachment as GL_TEXTURE_2D,
+                // which an array or cube attachment refuses - it answers 0, the size-derived
+                // guesses below take over, and the refusal must not be left on the error
+                // queue for the caller's next glGetError to pick up as its own.
                 const GLenum exact = ReplicateBlitImpl::QueryAttachmentSizedFormat(point);
+                ClearGLErrors();
                 if (exact != 0) {
                     out->Push(exact);
                     return true;

README.md

@@ -164,6 +164,7 @@ MobileGL supports runtime configuration via environment variables.
 | `MOBILEGL_MAGMA_FRAMESINFLIGHT` | Set Magma frames in flight. | Integer `1`–`64` | `3` |
 | `MOBILEGL_AVOID_SAMPLER_MIPMAP_MIN_FILTER` | Avoid sampler mipmap minification filters. | `0`, `1` | `0` |
 | `MOBILEGL_COHERENT_AS_FLUSH` | Treat persistent `GL_MAP_FLUSH_EXPLICIT_BIT` maps as coherent (app-compat for engines like Flywheel that never flush them). | `0`, `1` | `0` |
+| `MOBILEGL_ESPRYT_FORCE_DS_READBACK_EMULATION` | Always emulate depth/stencil `glReadPixels`/`glGetTexImage` by shader sampling on Espryt, instead of using the driver's own depth/stencil readback where it has one. | `0`, `1` | `0` |
 | `VK_ICD_FILENAMES`      | Select the Vulkan ICD used by the Vulkan loader. | Path to an ICD JSON file             | Loader default |
 
 ## License