Examples: DirectX9: Comments, updated changelog, notes about usage of imconfig.h (#1790, #1687)

CHANGELOG.txt

@@ -69,6 +69,7 @@ Other Changes:
 - Examples: Calling IMGUI_CHECKVERSION() in the main.cpp of every example application.
 - Examples: Allegro 5: Added support for 32-bit indices setup via defining ImDrawIdx, to avoid an unnecessary conversion (Allegro 5 doesn't support 16-bit indices).
 - Examples: Allegro 5: Renamed bindings from imgui_impl_a5.cpp to imgui_impl_allegro5.cpp.
+- Examples: DirectX 9 : Saving/restoring Transform because they don't seem to be included in the StateBlock. Setting shading mode to Gouraud. (#1790, #1687) [@sr-tream]
 - Various minor fixes, tweaks, refactoring, comments.
 
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examples/directx9_example/imgui_impl_dx9.cpp

@@ -10,6 +10,7 @@
 
 // CHANGELOG 
 // (minor and older changes stripped away, please see git history for details)
+//  2018-05-07: Render: Saving/restoring Transform because they don't seem to be included in the StateBlock. Setting shading mode to Gouraud.
 //  2018-03-20: Misc: Setup io.BackendFlags ImGuiBackendFlags_HasMouseCursors and ImGuiBackendFlags_HasSetMousePos flags + honor ImGuiConfigFlags_NoMouseCursorChange flag.
 //  2018-02-20: Inputs: Added support for mouse cursors (ImGui::GetMouseCursor() value and WM_SETCURSOR message handling).
 //  2018-02-16: Misc: Obsoleted the io.RenderDrawListsFn callback and exposed ImGui_ImplDX9_RenderDrawData() in the .h file so you can call it yourself.
@@ -76,13 +77,16 @@ void ImGui_ImplDX9_RenderDrawData(ImDrawData* draw_data)
     if (g_pd3dDevice->CreateStateBlock(D3DSBT_ALL, &d3d9_state_block) < 0)
         return;
 
-    // Backup the DX9 transform
+    // 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);
 
-    // Copy and convert all vertices into a single contiguous buffer
+    // Copy and convert all vertices into a single contiguous buffer, convert colors to DX9 default format.
+    // FIXME-OPT: This is a waste of resource, the ideal is to use imconfig.h and
+    //  1) to avoid repacking colors:   #define IMGUI_USE_BGRA_PACKED_COLOR
+    //  2) to avoid repacking vertices: #define IMGUI_OVERRIDE_DRAWVERT_STRUCT_LAYOUT struct ImDrawVert { ImVec2 pos; float z; ImU32 col; ImVec2 uv; }
     CUSTOMVERTEX* vtx_dst;
     ImDrawIdx* idx_dst;
     if (g_pVB->Lock(0, (UINT)(draw_data->TotalVtxCount * sizeof(CUSTOMVERTEX)), (void**)&vtx_dst, D3DLOCK_DISCARD) < 0)
@@ -98,7 +102,7 @@ void ImGui_ImplDX9_RenderDrawData(ImDrawData* draw_data)
             vtx_dst->pos[0] = vtx_src->pos.x;
             vtx_dst->pos[1] = vtx_src->pos.y;
             vtx_dst->pos[2] = 0.0f;
-            vtx_dst->col = (vtx_src->col & 0xFF00FF00) | ((vtx_src->col & 0xFF0000)>>16) | ((vtx_src->col & 0xFF) << 16);     // RGBA --> ARGB for DirectX9
+            vtx_dst->col = (vtx_src->col & 0xFF00FF00) | ((vtx_src->col & 0xFF0000) >> 16) | ((vtx_src->col & 0xFF) << 16);     // RGBA --> ARGB for DirectX9
             vtx_dst->uv[0] = vtx_src->uv.x;
             vtx_dst->uv[1] = vtx_src->uv.y;
             vtx_dst++;