[Fix] (MG_Backend/DirectGLES, MG_Impl/GLImpl): ReadPixels - fall back to wide-format conversion when the ES driver rejects a legacy native read combo (Adreno errors on e.g. GL_RED/GL_UNSIGNED_INT and leaves the buffer untouched), and enforce packed-type/format pairing at the state layer via shared ValidateClientFormatTypePairing (GL_RED + GL_UNSIGNED_SHORT_5_6_5 now raises GL_INVALID_OPERATION)

MobileGL/MG_Impl/GLImpl/Framebuffer/GL_Framebuffer.cpp

@@ -1681,6 +1681,13 @@ namespace MobileGL::MG_Impl::GLImpl {
             }
         }
 
+        // Packed-type/format pairing (GL CTS packed_pixels: e.g. GL_RED with GL_UNSIGNED_SHORT_5_6_5 must
+        // raise an error instead of reaching the backend). Shared with the TexImage/GetTexImage validators;
+        // runs after the depth-stencil branch above so DEPTH_STENCIL with a wrong type keeps GL_INVALID_ENUM.
+        if (!TextureImpl::ValidateClientFormatTypePairing(textureInputFormat, texturePixelDataType)) {
+            return false;
+        }
+
         // Check PBO state
         const auto& pixelPackBufferObject =
             MG_State::pGLContext->GetBufferBindingSlot(BufferTarget::PixelPack).GetBoundObject();

MobileGL/MG_Impl/GLImpl/Texture/Validators.cpp

@@ -235,17 +235,15 @@ namespace MobileGL::MG_Impl::GLImpl::TextureImpl {
                format == TextureInputFormat::StencilIndex;
     }
 
-    // Mirrors the desktop-GL validity matrix used by GL CTS packed_pixels (glcPackedPixelsTests
-    // isFormatValid, INPUT_TEXIMAGE): packed-type/format pairing, depth-vs-color mismatch, and
-    // integer-ness matching all raise GL_INVALID_OPERATION instead of reaching the upload path.
-    Bool ValidateTextureInternalFormatCompatibleWithInput(TextureInputFormat format,
-                                                          TextureInternalFormat internalFormat,
-                                                          TexturePixelDataType type) {
+    // Client-memory format<->type pairing rules shared by pixel uploads (TexImage*) and readbacks
+    // (ReadPixels, GetTexImage). Mirrors the desktop-GL validity matrix used by GL CTS packed_pixels
+    // (glcPackedPixelsTests isFormatValid): packed types constrain the formats they may pair with, and
+    // integer formats reject floating-point types; violations raise GL_INVALID_OPERATION.
+    Bool ValidateClientFormatTypePairing(TextureInputFormat format, TexturePixelDataType type) {
         const auto recordInvalidOperation = [](const char* message) {
             MG_State::pGLContext->RecordError(
                 ErrorCode::InvalidOperation,
-                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", "ValidateTextureInternalFormatCompatibleWithInput",
-                                             message));
+                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", "ValidateClientFormatTypePairing", message));
             return false;
         };
 
@@ -288,6 +286,27 @@ namespace MobileGL::MG_Impl::GLImpl::TextureImpl {
             return recordInvalidOperation("Integer format cannot be used with a floating-point type");
         }
 
+        return true;
+    }
+
+    // Mirrors the desktop-GL validity matrix used by GL CTS packed_pixels (glcPackedPixelsTests
+    // isFormatValid, INPUT_TEXIMAGE): packed-type/format pairing, depth-vs-color mismatch, and
+    // integer-ness matching all raise GL_INVALID_OPERATION instead of reaching the upload path.
+    Bool ValidateTextureInternalFormatCompatibleWithInput(TextureInputFormat format,
+                                                          TextureInternalFormat internalFormat,
+                                                          TexturePixelDataType type) {
+        const auto recordInvalidOperation = [](const char* message) {
+            MG_State::pGLContext->RecordError(
+                ErrorCode::InvalidOperation,
+                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", "ValidateTextureInternalFormatCompatibleWithInput",
+                                             message));
+            return false;
+        };
+
+        if (!ValidateClientFormatTypePairing(format, type)) {
+            return false;
+        }
+
         // TexImage in core 3.3 has no stencil-only upload path (that arrived with GL 4.4).
         if (format == TextureInputFormat::StencilIndex) {
             return recordInvalidOperation("STENCIL_INDEX is not a valid texture upload format");

MobileGL/MG_Impl/GLImpl/Texture/Validators.h

@@ -23,6 +23,7 @@ namespace MobileGL::MG_Impl::GLImpl::TextureImpl {
     Bool ValidateTextureSizeRange(Int width, Int height, Int depth);
     Bool ValidateTextureInternalFormat(TextureInternalFormat format);
     Bool ValidateTextureBorderNumber(Int border);
+    Bool ValidateClientFormatTypePairing(TextureInputFormat format, TexturePixelDataType type);
     Bool ValidateTextureInternalFormatCompatibleWithInput(TextureInputFormat format,
                                                           TextureInternalFormat internalFormat,
                                                           TexturePixelDataType type);