gpu: fix the computed element count in DrawIndexedElements on Direct3D.

src/gpu/vertexbuffer.cpp

@@ -199,20 +199,24 @@ void VertexDeclaration::DrawIndexedElements(MeshPrimitive type, int vbase,
     g_d3ddevice->SetRenderState(D3DRS_ALPHABLENDENABLE, 1);
     g_d3ddevice->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_SRCALPHA);
     g_d3ddevice->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_INVSRCALPHA);
-    g_d3ddevice->SetRenderState(D3DRS_CULLMODE, D3DCULL_CW);
+    if (FAILED(g_d3ddevice->SetRenderState(D3DRS_CULLMODE, D3DCULL_CW)))
+        Abort();
     switch (type)
     {
     case MeshPrimitive::Triangles:
+        count = count / 3;
         if (FAILED(g_d3ddevice->DrawIndexedPrimitive(D3DPT_TRIANGLELIST,
                                            vbase, vskip, vcount, skip, count)))
             Abort();
         break;
     case MeshPrimitive::TriangleStrips:
+        count = count - 2;
         if (FAILED(g_d3ddevice->DrawIndexedPrimitive(D3DPT_TRIANGLESTRIP,
                                            vbase, vskip, vcount, skip, count)))
             Abort();
         break;
     case MeshPrimitive::TriangleFans:
+        count = count - 2;
         if (FAILED(g_d3ddevice->DrawIndexedPrimitive(D3DPT_TRIANGLEFAN,
                                            vbase, vskip, vcount, skip, count)))
             Abort();