diff --git a/HANDOFF_DILIGENT.md b/HANDOFF_DILIGENT.md
index e053042f..36674a97 100644
--- a/HANDOFF_DILIGENT.md
+++ b/HANDOFF_DILIGENT.md
@@ -157,6 +157,7 @@ Verified locally on Turnip Adreno 750:
   - `ClearBufferfv` / `ClearBufferfi` / `ClearBufferiv` / `ClearBufferuiv` (incl. stencil clear)
   - `BlitFramebuffer` (same-size color copy between current read/draw FBOs)
   - `CopyTexImage2D` / `CopyTexSubImage2D` (whole-color copy fallback)
+  - `CopyImageSubData` (whole-texture copy between two texture objects)
   - `GetTexImage` / `GetTextureImage` (RGBA8 readback)
   - `ReadPixels` from default and user color attachments
 - Primitive expansion:
@@ -250,7 +251,7 @@ Notes:
    - [x] `MultiDraw*`
    - [x] `BlitFramebuffer` (same-size color copy)
    - [x] `ReadPixels` from non-default framebuffer
-   - [x] `CopyTexImage*` wired as whole-color copy
+   - [x] `CopyTexImage*` / `CopyImageSubData` wired as whole-resource copies
    - [x] `GetTexImage` / `GetTextureImage` (RGBA8)
    - [x] Indirect draws (CPU fallback)
 
diff --git a/MobileGL/MG_Backend/Diligent/BackendObject_Diligent.cpp b/MobileGL/MG_Backend/Diligent/BackendObject_Diligent.cpp
index 931d5d45..4bcdb093 100644
--- a/MobileGL/MG_Backend/Diligent/BackendObject_Diligent.cpp
+++ b/MobileGL/MG_Backend/Diligent/BackendObject_Diligent.cpp
@@ -515,6 +515,30 @@ namespace MobileGL::MG_Backend::DiligentBackend {
             renderer->ReadTextureImage(*texture, static_cast<Uint32>(level), pixels);
         }
 
+        void CopyImageSubData(const SharedPtr<MG_State::GLState::ITextureObject>& srcTexture,
+                              GLenum srcTarget, GLint srcLevel, GLint srcX, GLint srcY, GLint srcZ,
+                              const SharedPtr<MG_State::GLState::ITextureObject>& dstTexture,
+                              GLenum dstTarget, GLint dstLevel, GLint dstX, GLint dstY, GLint dstZ,
+                              GLsizei srcWidth, GLsizei srcHeight, GLsizei srcDepth) {
+            (void)srcTarget;
+            (void)srcLevel;
+            (void)srcX;
+            (void)srcY;
+            (void)srcZ;
+            (void)dstTarget;
+            (void)dstLevel;
+            (void)dstX;
+            (void)dstY;
+            (void)dstZ;
+            (void)srcWidth;
+            (void)srcHeight;
+            (void)srcDepth;
+            auto* renderer = GetActiveRenderer();
+            if (renderer != nullptr && srcTexture && dstTexture) {
+                renderer->CopyTextureSubData(*srcTexture, *dstTexture);
+            }
+        }
+
         void Present() {
             auto* renderer = GetActiveRenderer();
             if (renderer != nullptr) {
@@ -628,6 +652,7 @@ namespace MobileGL::MG_Backend::DiligentBackend {
         m_functions.GL.BlitFramebuffer = BlitFramebuffer;
         m_functions.GL.CopyTexImage2D = CopyTexImage2D;
         m_functions.GL.CopyTexSubImage2D = CopyTexSubImage2D;
+        m_functions.GL.CopyImageSubData = CopyImageSubData;
         m_functions.GL.GetTexImage = GetTexImage;
         m_functions.GL.GetTextureImage = GetTextureImage;
         m_functions.GL.ReadPixels = ReadPixels;
diff --git a/MobileGL/MG_Backend/Diligent/Renderer/DiligentRenderer.cpp b/MobileGL/MG_Backend/Diligent/Renderer/DiligentRenderer.cpp
index 61d7a0ce..bc9b34bc 100644
--- a/MobileGL/MG_Backend/Diligent/Renderer/DiligentRenderer.cpp
+++ b/MobileGL/MG_Backend/Diligent/Renderer/DiligentRenderer.cpp
@@ -1816,6 +1816,29 @@ void main()
         m_pContext->CopyTexture(copyAttribs);
     }
 
+    void DiligentRenderer::CopyTextureSubData(MG_State::GLState::ITextureObject& src,
+                                           MG_State::GLState::ITextureObject& dst) {
+        if (!m_initialized || !m_pContext) {
+            return;
+        }
+        if (SyncTexture(src) == nullptr || SyncTexture(dst) == nullptr) {
+            return;
+        }
+        auto srcIt = m_textureCache.find(src.GetLifetimeId());
+        auto dstIt = m_textureCache.find(dst.GetLifetimeId());
+        if (srcIt == m_textureCache.end() || dstIt == m_textureCache.end() ||
+            !srcIt->second.Texture || !dstIt->second.Texture) {
+            return;
+        }
+        if (srcIt->second.Texture == dstIt->second.Texture) {
+            return;
+        }
+        ::Diligent::CopyTextureAttribs copyAttribs(
+            srcIt->second.Texture, ::Diligent::RESOURCE_STATE_TRANSITION_MODE_TRANSITION,
+            dstIt->second.Texture, ::Diligent::RESOURCE_STATE_TRANSITION_MODE_TRANSITION);
+        m_pContext->CopyTexture(copyAttribs);
+    }
+
     Bool DiligentRenderer::ReadTextureImage(MG_State::GLState::ITextureObject& texture, Uint32 level,
                                          void* pixels) {
         if (!m_initialized || !m_pContext || pixels == nullptr) {
diff --git a/MobileGL/MG_Backend/Diligent/Renderer/DiligentRenderer.h b/MobileGL/MG_Backend/Diligent/Renderer/DiligentRenderer.h
index 92268af7..fdf1075e 100644
--- a/MobileGL/MG_Backend/Diligent/Renderer/DiligentRenderer.h
+++ b/MobileGL/MG_Backend/Diligent/Renderer/DiligentRenderer.h
@@ -66,6 +66,7 @@ namespace MobileGL::MG_Backend::DiligentBackend {
                              GLint dstX0, GLint dstY0, GLint dstX1, GLint dstY1,
                              GLbitfield mask, GLenum filter);
         void CopyReadFramebufferToTexture(MG_State::GLState::ITextureObject& dst);
+        void CopyTextureSubData(MG_State::GLState::ITextureObject& src, MG_State::GLState::ITextureObject& dst);
         Bool ReadTextureImage(MG_State::GLState::ITextureObject& texture, Uint32 level, void* pixels);
         void Present();