Render Context

Overview

A Render Context (Halley::RenderContext) is an abstraction that configures how you're going to perform rendering. It can be passed around, and is immutable, however you can create modified versions of it with the with() family of methods. To actually draw with a given context, you can use the bind() method.

Methods

with (Camera)

RenderContext RenderContext::with(Camera& camera) const;

Returns a copy of the current context, but using the provided Camera instead. Use this to perform zooming and scrolling, for example.

with (RenderTarget)

RenderContext RenderContext::with(RenderTarget& target) const;

Returns a copy of the current context, but using the provided Render Target instead. Use this to render to a texture, for example.

bind

void RenderContext::bind(std::function<void(Painter&)> f);

Binds the render context, invokes the provided function (which will receive a valid Painter reference), then unbinds the render context. Use this to perform actual drawing.

Note that you shouldn't use any render contexts inside this callback.

Example

void MyStage::onRender(RenderContext& context) const
{
	auto screenCam = Camera(Vector2f(currentResolution) * 0.5f);

	context.with(screenCam).bind([&](Painter& painter)
	{
		painter.clear(Colour(0, 0, 0, 1.0f));
		Sprite()
			.setImage(getResources(), "test.png")
			.setPos(Vector2f(currentResolution) * 0.25f)
			.draw(painter);
	});
}