FyroxEngine/Fyrox · error

only rectangle textures can be used as render target!

Error message

only rectangle textures can be used as render target!

What it means

Engine::update derives the frame size from the scene render target; if a render-target texture is set, it must be a Rectangle texture. Any other TextureKind (e.g. D2, Cube) panics because its dimensions cannot be used as a framebuffer size.

Solutions

1. Build the render-target texture with TextureKind::Rectangle { width, height }
2. Verify rt.data_ref().kind() is Rectangle before assigning it as render target
3. Leave render_target as None to use the window backbuffer size

Example fix

// before
let tex = TextureBuilder::new().with_kind(TextureKind::D2 { width: 1024, height: 768 })...
camera.set_render_target(Some(tex));
// after
let tex = TextureBuilder::new().with_kind(TextureKind::Rectangle { width: 1024, height: 768 })...
camera.set_render_target(Some(tex));

assert!(matches!(rt.data_ref().kind(), TextureKind::Rectangle{..}), "render target must be a Rectangle texture");

fn rect_size(t: &Texture) -> Option<Vector2<u32>> { if let TextureKind::Rectangle{width,height} = t.kind() { Some(Vector2::new(width,height)) } else { None } }

When it happens

Trigger: Assigning a texture whose kind is not TextureKind::Rectangle to camera render_target (or the engine render target) and then running Engine::update.

Common situations: Using TextureBuilder with kind D2 for an offscreen render target; reusing a sampled 2D texture as a render target; version differences where render targets required Rectangle kinds.

Understand the failure class

Background: "is not a compatible type" / "cannot merge" errors: when a value's type doesn't match what the library requires — this error's family across 65 libraries.

Related errors

• only rectangle textures can be used as render target!
• Missing hole mask texture
• Graphics context is uninitialized!
• Graph pool must be empty on load!
• Invalid pixel position

AI-assisted analysis of FyroxEngine/Fyrox@76c91aad8e (2026-09-10). Data as JSON: /api/errors/1a9f4457d3342d9b. Report an issue: GitHub.

Appendix: source

Thrown at fyrox-impl/src/engine/mod.rs:1723

            let inner_size = ctx.window.inner_size();
            let window_size = Vector2::new(inner_size.width as f32, inner_size.height as f32);
            ctx.renderer.update_caches(&self.resource_manager, dt);
            window_size
        } else {
            Vector2::new(1.0, 1.0)
        };

        for (handle, scene) in self.scenes.pair_iter_mut().filter(|(_, s)| *s.enabled) {
            let frame_size =
                scene
                    .rendering_options
                    .render_target
                    .as_ref()
                    .map_or(window_size, |rt| {
                        if let TextureKind::Rectangle { width, height } = rt.data_ref().kind() {
                            Vector2::new(width as f32, height as f32)
                        } else {
                            panic!("only rectangle textures can be used as render target!");
                        }
                    });

            scene.update(
                frame_size,
                dt,
                switches.get(&handle).cloned().unwrap_or_default(),
            );
        }
    }

    /// Performs post update for the engine.
    ///
    /// Normally, this is called from `Engine::update()`.
    /// You should only call this manually if you don't use that method.
    pub fn post_update(
        &mut self,
        dt: f32,

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