NVPR Cursive Text Sample

Category: Visuals

Min PC GPU: GeForce Fermi-class

Min Tegra Device: Tegra K1

@ GitHub: NVPR Cursive Text Sample Source Code

Description

This sample demonstrates how to use NV_path_rendering to animate the dash pattern of a stroked path, as a way to simulate live cursive writing.

APIs Used

NV_path_rendering
EXT_direct_state_access

Shared User Interface

The Graphics samples all share a common app framework and certain user interface elements, centered around the "Tweakbar" panel on the left side of the screen which lets you interactively control certain variables in each sample.

To show and hide the Tweakbar, simply click or touch the triangular button positioned in the top-left of the view.

Other controls are listed below.

Device	Input	Result
touch	2-Finger Drag	Translate the view
	2-Finger Pinch	Scale the view
mouse	Left-Click Drag	Translate the view
	Right-Click Drag	Scale the view (up:out, down:in)
keyboard	Esc	Quit the application
	Tab	Toggle TweakBar visibility
gamepad	Start	Toggle TweakBar visibility
	A	Show TweakBar, Toggle Focused Item
	B	Close Focused UI, Hide TweakBar
	DPAD Up/Down	Move Focus to Prev/Next Item
	DPAD Left/Right	Decrease/Increase Focused Item

App-Specific Controls

This sample has the following app-specific controls:

Device	Input	Result
keyboard	space	Toggle Animation
	R	Reset Scene
	, / .	Decrease/Increase Animation State
gamepad	Y	Toggle Animation
	X	Reset Scene
	DPAD Left/Right	Decrease/Increase Animation State

Technical Details

An outline for the text "This is crazy" is drawn incrementally by computing the total arc length of the path using glGetPathLengthNV and then setting the dash pattern with glPathDashArrayNV to be some percentage of that total path length. By animating the dash pattern in this way, the stroking of the path appears to animate in way to trace out the path's outline.