simvx.graphics.presentation

Where on the swapchain the scene’s space is drawn.

SceneTree.content_scale_mode decides the space the scene is laid out in. Under EXPAND that space is the window, so the scene is drawn across the whole swapchain and this module is the identity. Under FIT the scene is laid out at a design resolution and presented scaled uniformly and centred, with letterbox or pillarbox bars in the margin, and the renderer has to be told the sub-rect to draw into and the size of the space it is drawing.

The rect comes from :attr:SceneTree.presentation_rect, which is the inverse of the conversion the input router applies to every incoming pointer, so a control is hit where it is drawn by construction rather than by two placements agreeing. What this module adds is the conversion to physical pixels: the tree measures the glass in engine units and the swapchain is a pixel grid, and the ratio between them is taken from the extent rather than from the window’s reported content scale so the rect can never fall outside the framebuffer.

Module Contents

Classes

Presentation

The swapchain sub-rect the scene is presented into, and its own size.

Functions

presentation_for

Where tree is presented on a swapchain of extent physical pixels.

Data

__all__

API

simvx.graphics.presentation.__all__

[‘Presentation’, ‘presentation_for’]

class simvx.graphics.presentation.Presentation(rect: tuple[int, int, int, int], ui_size: tuple[float, float], letterboxed: bool)

The swapchain sub-rect the scene is presented into, and its own size.

rect is (x, y, width, height) in physical swapchain pixels; ui_size is the size of the space the scene laid itself out in, in engine units, which is what the 2D lanes divide vertex positions by. letterboxed is False whenever the rect is the whole swapchain, which is every EXPAND frame and a FIT frame whose window happens to match the design aspect: the draw sites read it to stay on their original path.

Initialization

__slots__

(‘rect’, ‘ui_size’, ‘letterboxed’)

__repr__() → str

simvx.graphics.presentation.presentation_for(tree: Any, extent: tuple[int, int] | None) → simvx.graphics.presentation.Presentation | None

Where tree is presented on a swapchain of extent physical pixels.

The whole extent under EXPAND. Under FIT the design rect placed by

Attr:

SceneTree.presentation_rect, converted to pixels by the extent over the glass and clamped inside it so a rounding step can never hand Vulkan a viewport that leaves the framebuffer.

None when there is no swapchain yet (Engine.extent before Vulkan is initialised), which every draw site already reads as “the whole target”.