Backends: DX9: programmable rendering pipeline: 6.state backup & restore

backends/imgui_impl_dx9.cpp

@@ -198,6 +198,9 @@ static IDirect3DVertexBuffer9*      g_pVB              = NULL;
 static IDirect3DIndexBuffer9*       g_pIB              = NULL;
 static int                          g_VertexBufferSize = 4096;
 static int                          g_IndexBufferSize  = 8192;
+// Direct3D9 state
+static IDirect3DStateBlock9*        g_pd3dState        = NULL;
+static D3DMATRIX                    g_LastMVP[3];
 // Direct3D9 programmable rendering pipeline data
 static bool                         g_IsShaderPipeline = false;
 static IDirect3DVertexDeclaration9* g_pInputLayout     = NULL;
@@ -210,6 +213,43 @@ static const char* IMGUI_IMPL_D3D9_BACKEND_NAME_FIXED = "imgui_impl_dx9 (fixed)"
 static const char* IMGUI_IMPL_D3D9_BACKEND_NAME_SHADER = "imgui_impl_dx9 (shader)";
 
 // Setup render state
+// According to Microsoft's official documents, IDirect3DStateBlock9 should store all states,
+// but according to the actual test, it seems to only store dirty states.
+// We have to backup some states manually. Only support those device create without D3DCREATE_PUREDEVICE flag!
+static void ImGui_ImplDX9_BackupState()
+{
+    // Backup the DX9 transform
+    if (!g_IsShaderPipeline)
+    {
+        g_pd3dDevice->GetTransform(D3DTS_WORLD, &g_LastMVP[0]);
+        g_pd3dDevice->GetTransform(D3DTS_VIEW, &g_LastMVP[1]);
+        g_pd3dDevice->GetTransform(D3DTS_PROJECTION, &g_LastMVP[2]);
+    }
+    else
+    {
+        g_pd3dDevice->GetVertexShaderConstantF(0, (float*)&g_LastMVP[0], 4);
+    }
+
+    // Backup the DX9 state
+    g_pd3dState->Capture();
+}
+static void ImGui_ImplDX9_RestoreState()
+{
+    // Restore the DX9 transform
+    if (!g_IsShaderPipeline)
+    {
+        g_pd3dDevice->SetTransform(D3DTS_WORLD, &g_LastMVP[0]);
+        g_pd3dDevice->SetTransform(D3DTS_VIEW, &g_LastMVP[1]);
+        g_pd3dDevice->SetTransform(D3DTS_PROJECTION, &g_LastMVP[2]);
+    }
+    else
+    {
+        g_pd3dDevice->SetVertexShaderConstantF(0, (float*)&g_LastMVP[0], 4);
+    }
+
+    // Restore the DX9 state
+    g_pd3dState->Apply();
+}
 static void ImGui_ImplDX9_SetupRenderState(ImDrawData* draw_data)
 {
     IDirect3DDevice9* ctx = g_pd3dDevice;
@@ -491,18 +531,8 @@ void ImGui_ImplDX9_RenderDrawData(ImDrawData* draw_data)
     if (!ImGui_ImplDX9_CreateBuffers(draw_data))
         return;
 
-    // Backup the DX9 transform (DX9 documentation suggests that it is included in the StateBlock but it doesn't appear to)
-    D3DMATRIX last_world, last_view, last_projection;
-    g_pd3dDevice->GetTransform(D3DTS_WORLD, &last_world);
-    g_pd3dDevice->GetTransform(D3DTS_VIEW, &last_view);
-    g_pd3dDevice->GetTransform(D3DTS_PROJECTION, &last_projection);
-
-    // Backup the DX9 state
-    IDirect3DStateBlock9* d3d9_state_block = NULL;
-    if (D3D_OK != g_pd3dDevice->CreateStateBlock(D3DSBT_ALL, &d3d9_state_block))
-        return;
-
     // Setup desired DX state
+    ImGui_ImplDX9_BackupState();
     ImGui_ImplDX9_SetupRenderState(draw_data);
 
     // Render command lists
@@ -537,14 +567,8 @@ void ImGui_ImplDX9_RenderDrawData(ImDrawData* draw_data)
         global_vtx_offset += cmd_list->VtxBuffer.Size;
     }
 
-    // Restore the DX9 transform
-    g_pd3dDevice->SetTransform(D3DTS_WORLD, &last_world);
-    g_pd3dDevice->SetTransform(D3DTS_VIEW, &last_view);
-    g_pd3dDevice->SetTransform(D3DTS_PROJECTION, &last_projection);
-
-    // Restore the DX9 state
-    d3d9_state_block->Apply();
-    d3d9_state_block->Release();
+    // Restore DX state
+    ImGui_ImplDX9_RestoreState();
 }
 
 bool ImGui_ImplDX9_Init(IDirect3DDevice9* device)
@@ -573,6 +597,8 @@ bool ImGui_ImplDX9_CreateDeviceObjects()
 {
     if (!g_pd3dDevice)
         return false;
+    if (D3D_OK != g_pd3dDevice->CreateStateBlock(D3DSBT_ALL, &g_pd3dState))
+        return false;
     if (!ImGui_ImplDX9_CreateFontsTexture())
         return false;
     g_IsShaderPipeline = ImGui_ImplDX9_CreateShaderPipeline(); // Shader pipeline is optional
@@ -591,6 +617,7 @@ void ImGui_ImplDX9_InvalidateDeviceObjects()
     SAFE_RELEASE(g_pIB);
     g_VertexBufferSize = 4096;
     g_IndexBufferSize  = 8192;
+    SAFE_RELEASE(g_pd3dState);
     g_IsShaderPipeline = false;
     SAFE_RELEASE(g_pInputLayout);
     SAFE_RELEASE(g_pVertexShader);