Engine Drawing

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• Draw with UCanvas
  • Draw a text
  • Draw a line
  • Draw a box
• Use AHUD to draw
  • Get AHUD
  • Draw a rectangle

Draw with UCanvas

If we hook the PostRender function from UGameViewportClient, we got a UCanvas pointer that comes as parameter.

Draw a text

UCanvas*->K2_DrawText

// Get somewhere at the beginning the font once
auto defaultFont = UObject::FindObject<UFont>("Font Roboto.Roboto");
// ...
auto myText = std::wstring(L"Hallo World");
canvas->K2_DrawText(defaultFont, FString(myText.c_str()), FVector2D(100, 100), White, 1.f, Black, FVector2D(1.f, 1.f), true, true, true, Black);

Draw a line

UCanvas*->K2_DrawLine

FLinearColor white(1.f,1.f,1.f,1.f);
canvas->K2_DrawLine(FVector2D(10, 10), FVector2D(100, 100), 1.f, white);

Draw a box

UCanvas*->K2_DrawBox can draw only white boxes, so we have make an own function.

void DrawBox(UCanvas* canvas, const FVector2D& min, const FVector2D& max, const FLinearColor& color, float thickness)
{
    canvas->K2_DrawLine(min, FVector2D(max.X, min.Y), thickness, color); // top border
    canvas->K2_DrawLine(min, FVector2D(min.X, max.Y), thickness, color); // left border
    canvas->K2_DrawLine(FVector2D(min.X, max.Y), max, thickness, color); // bottom border
    canvas->K2_DrawLine(FVector2D(max.X, min.Y), max, thickness, color); // right border
}
// usage
FLinearColor red(1.f, 0, 0, 1.f);
DrawBox(canvas, FVector2D(10, 10), FVector2D(100, 100), red, 1.f);

Use AHUD to draw

Assign the current UCanvas from the PostRender function, then you can draw with AHUD.

Get AHUD

PlayerController->MyHUD

Draw a rectangle

PlayerController->MyHUD->Canvas = canvas;
PlayerController->MyHUD->DrawRect(color, x, y, width, heigth);