NVPR Tiger Warp Sample

Category: Visuals

Min PC GPU: GeForce Fermi-class

Min Tegra Device: Tegra K1

@ GitHub: NVPR Tiger Warp Sample Source Code

Description

This samples draws the so-called 'PostScript Tiger' artwork, consisting of 240 paths specified as cubic Bezier curves and line segments.

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
	F	Toggle Path Fill
	S	Toggle Path Stroke
	, / .	Font Size -/+
gamepad	Y	Toggle Animation
	X	Reset Scene
	Left Shoulder Button	Toggle Path Fill
	Right Shoulder Button	Toggle Path Stroke
	DPAD Left/Right	Font Size -/+

Technical Details

This sample demonstrates NV_path_rendering drawing the classic 'PostScript Tiger' vector image.

The user interface includes four control points at the corners that you can drag interactively, which determine how the tiger is projectively warped in 3D.

The utility function quad2quad provides a matrix that maps corners of the bounds of the tiger based on the interactively repositioned corner points. This provides a modelview matrix that is loaded into OpenGL using glMatrixLoadfEXT.