Mercury Sample

Category: Visuals

Min PC GPU: GeForce Kepler-class

Min Tegra Device: Tegra K1

@ GitHub: Mercury Sample Source Code

Description

This sample demonstrates how to use compute shaders to generate and render particle-based implicit surfaces.

APIs Used

OpenGL ES 3.1

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	1-Finger Drag	Orbit-rotate the camera
	2-Finger Drag	Move up/down/left/right
	2-Finger Pinch	Scale the view
mouse	Left-Button Drag	Orbit-rotate the camera
	Right-Button Drag	Move up/down/left/right
	Middle-Click Drag	Scale the view (up:out, down:in)
keyboard	Escape	Quit the application
	Tab	Toggle TweakBar visibility
gamepad	Start	Toggle TweakBar visibility
	Right ThumbStick	Orbit-rotate the camera
	Left ThumbStick	Move forward/backward, Slide left/right
	Left/Right Triggers	Move up/down
	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

Technical Details

Introduction

The Mercury sample has an implementation of 3D metaballs using the Marching Cubes algorithm with a physics driven particle system that drives the metaballs. The data-set is manipulated using a compute shader and another compute shader is used to calculate isovalues used by the Marching Cubes algorithm.

Particle Field

The particles themselves are updated using a fluid simulation compute shader.

The 3D sampled potential field is generated from the particles via a compute shader (iterating/summing over all particles per sample), stored in a shader storage buffer

Triangle Generator

The generation of triangles for the algorithm is done in a geometry shader that uses a triangle topology table.

Shading

The sample also uses a deferred shading making use of a gbuffer with multiple attachments for albedo, normals, world space coordinates, etc. Currently the deferred path is not making full use of these attachments for post effects but these will be added in a future release.