HOW CRYENGINE 3 AND AMD GCN ARCHITECTURE GAVE BIRTH TO A RED GEM: "PROJECT PHOENIX" Bill Bilodeau Developer Relations Engineer AMD Kedhrin Gonzalez Creative

HOW CRYENGINE 3 AND AMD GCN ARCHITECTURE GAVE BIRTH TO A RED GEM: "PROJECT PHOENIX"

Bill Bilodeau Developer Relations EngineerAMD

Kedhrin GonzalezCreative DirectorIllfonic

Sean TracySenior Field Applications EngineerCrytek

Dongsoo HanSoftware Research EngineerAMD

3| Project Phoenix | March 27, 2013

Creating A New Ruby


CREATING A NEW RUBY

Re-imagining an icon

– Ruby in the past

– New design

Cinematic Feel

– Established Partners

– Making a game cinematic

Authoring Tools

– Tools Used

– TressFX

Leveraging Technology

– CryENGINE 3

– Mesh Tessellation


RE-IMAGINING AN ICON | RUBY IN THE PAST

Ruby through the ages

– Showcasing new technology

– Anime Style


RE-IMAGINING AN ICON | NEW DESIGN

New Design

– Modern look and design

– Realistic “combat ready” Ruby

– Based off realism

– Showcase materials and tech


RE-IMAGINING AN ICON | NEW DESIGN

Showcase Materials and Lighting


CINEMATIC FEEL | ESTABLISHED PARTNERS

The Graphic Film Company

– Simon West Directed

– Experienced Film Team

– Editing, Cinematography, and Animation Support

Digital Domain

– Body Motion Capture

– Facial Motion Capture

Art Bully Productions

– Outsourced Character Models

87Eleven

– Stunts and Fight Scenes


CINEMATIC FEEL | MAKING A GAME CINEMATIC

Make a game first, cinematic second

– Environment built like a game

– Focusing on Next Gen

– High pixel density assets

– Detailed Backgrounds

– Assets that can be reused

– New techniques


AUTHORING TOOLS | TOOLS USED

Tools Used

– 3D Studio Max, Maya, Mudbox, Crazybump, nDo 2, dDo, Zbrush, Photoshop, Illustrator, Motionbuilder, Shave and a Haircut

– Full Body Motion Capture

– Facial Motion Capture

– CryENGINE 3


AUTHORING TOOLS | TRESS FX

Tress FX

– Created hair in Maya using Shave and a Haircut

– Convert strands to NURB curves

– Export with Python script

– Import to Engine and finish settings


LEVERAGING TECHNOLOGY | CRYENGINE 3

Complete Toolset

– Lighting

– Animation

– FX

– Materials

Rapid Development

– Deployment from authoring tools

– Flexible Pipeline


LEVERAGING TECHNOLOGY | MESH TESSELLATION

Mesh Tessellation

– Gain Depth

– Planning for Phong

– Planning for Displacement


CRYENGINE 3 FEATURES LEVERAGED FOR PROJECT

PHOENIX "RUBY"


CRYENGINE FEATURES LEVERAGED FOR RUBY

Applied Lighting Technology

– Real-Time Area Lights with texture reflection

– Composite 3d Lens Flares and FX

– Spherical and Box Projected Image Based Lighting

Innovations in Shading and Rendering

– Screen Space Directional Occlusion – SSDO

– Real-Time Local Reflections – RLR

– Anti Aliasing for Ruby

– Eye Shader

Tessellation and Displacement

– Displacement Mapping

– Phong

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APPLIED LIGHTING TECHNOLOGY

Real-Time Area Lights with texture reflection

– Light sources in videogames are usually simulated analytically via an infinitely small point light source or directional light source when projection is required.

– This is a fairly good approximation for most cases, but in the real world light can come from anywhere and has a volume, this affects shadows and light reflection appearance.

– Many situations in Ruby when light sources cannot be simple points.

Billboards, Neon Lamps, Translucent materials

Too many point lights required to simulate these effects!

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Point Lights

Point lights cast infinitely Sharp shadows.

Real Shadows never look so sharp.

CryENGINE uses shadow maps which allows them to be slightly blurred with a fixed width.

Area Lights

Area Light is a light that has volume.

Its shadow starts sharp near to the object but blurs more and more at distance.

Much more physically plausible

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For the Ruby Project, the real-time area lights are used for artificial lighting, when the actual light sources are so large that their point-specular highlights would become a visual issue.

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Point Light Specular HighlightArea Light Highlight and Texture Reflection

Note the difference in specular highlight shape



Texture reflection and shape control

– The Ruby project also contains materials that are quite smooth and glossy as the environment is wet and in the rain.

– Area Lights are quite noticeable in this situation with the shape control over the specular highlights and with accurate texture reflection.

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Area Light Texture Reflection

Area Light Helper Shape

Area Light Helper Shape

Point Light Helper Shape



3d Composite Lens Flares

– Procedural Flares seem great, but in practice we need Artistic Input!

– A usual solution for such challenges is to hardcode a couple cases and that’s it.

– We created something much more user friendly and to help each project have its own look without a programmer having to write anything new.

– In Ruby, most key-lights are able to produce flares, orbs, streaks and other kind of visual aberrations due to the scratches and irregularities on the lens.

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3d Composite Lens Flares

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Composite Flare with 3 Sub Effects



No Flares



Image Based Lighting – IBL

– IBL is a rendering technique where complex lighting is stored in a environment map which is projected onto the scene.

Positive points:

– High quality

– Fast for many lights and even a complex environment is reflected

– Energy preserving specular power

Negative points

– Works only well for local positions with distant emitters and reflection content

– Static content only

In the CryENGINE IBL implementation diffuse lighting can be approximated very well by convolving an environment map (diffuse convolution) which is stored as a cube map again. Because of bilinear filtering, the texture can be quite low resolution as seen here.

Hard specular reflections are simple as a single texture lookup in the mirrored eye direction gives the lighting in that direction

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Depending on the light probe, the lighting can be more ambient or harsh or even colored. The following images show some examples (including sun which casts shadow)

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Box Projected Image Based Lighting – IBL

– Essential to the ruby demo was an advancement made for IBL probes called box projected IBL.

– This is a good technique for flat mirrors.

– In the Ruby demo this is how we achieving very accurate reflections without scrolling or rotating the IBL probe.

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Box Projection More Accurate Spherical Projection Less Accurate


SHADING AND RENDERING

Screen Space Directional Occlusion

– Contact Shadows or Screen Space Directional Occlusion (SSDO) is a novel technique developed for Crysis 2.

SSDO is more physically correct than our former technique SSAO.

We came up with a new implementation which is efficient enough to allow contact shadows to be applied from every light source in the world

SSDO can also help fixing self-shadowing issues and greatly improves the global lighting quality, especially when many different objects interact with each other from a lighting standpoint.

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SSDO OFF SSDO ON



Screen Space Directional Occlusion

– SSDO provides smooth “free” contact shadows that are especially noticeable when using ambient deferred lights which do not cast traditional shadow.

– It retains the color information and applies it to the contact shadow.

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SSDO Off SSDO On

Red and Blue Light is seen here bleeding into each other for Purple Contact Shadows



Real time Local reflections

– Reflections are one of the biggest challenges to solve efficiently in real-time rendering, particularly for deferred rendering/lighting based engines.

– We introduced a novel approach we call real-time local reflections (RLR).

RLR is a screen space approximation to ray-traced HDR reflections, from and on all objects on screen.

We use a ray marching technique combined with blur and jitter to disguise low sample counts.

Although the results are not always perfect this technique allows for any kind of curved surface in the scene to efficiently reflect the nearby surroundings in real time, including self-reflections which are not possible with cube maps or planar reflections.

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Real time Local reflections

– Currently uses 9 ray marched samples but was increased to 32 for Ruby as GCN Hardware manages the high sample count quite well because of efficient flow control hardware.

– Can be increased further as hardware becomes even more powerful.

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RLR Off RLR On @ 32 Samples



Anti Aliasing

– The latest engine iteration introduces the richest set of Anti aliasing options ever available within the CryENGINE.

Anti-Aliasing and its effectiveness can vary from user to user as some prefer a very sharp image, whilst others prefer a blurrier image.

– CryENGINE gives developers and their players all of the most effective and technically sophisticated modes to suit their preferences. Each mode has very different implications in terms of overall performance, quality and sharpness.

– The CryENGINE now supports the following anti-aliasing techniques with user controlled settings for number of samples and overall quality per mode.

FXAA (Fast-Aproximate Antialiasing)

SMAA (Subpixel Morphological Antialiasing)

MSAA (the foundation DX11 support for SMAA)

And also no AA, since surprisingly some users prefer no AA at all.

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Fast Approximate Anti-Aliasing – FXAA

– This is the mode with the best performance of the pack, while offering fairly reasonable image quality. It’s a post process solution, hence it doesn’t tackle any sub pixel information, some shimmering might be noticeable on slow camera movements due to lack of sub pixel movement.

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No AA FXAA



Improved Eye Shader

– The new eye shader uses Iris Parallax Mapping by default. The old alpha-blended method has been deprecated as it doesn't work with deferred lighting.

Luckily, fixing the assets requires very little work.

The new shader was designed with merged textures in mind (character head texture contains eyes and overlay in the same texture).

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TESSELLATION

Tessellation and Displacement

– One of the most important updates provided by the DirectX 11 API was the introduction of Programmable Hardware Tessellation.

– With the improvements to tessellation artists working on Ruby no longer had to go through a process of pre-tessellated their assets before seeing them in engine, thus allowing them to set tessellation in real-time by clicking a checkbox on a per-material basis

– Displacement mapping

Tessellates the mesh uniformly and Reads a displacement height map to extrude the vertices.

– Phong

Phong is an approximation technique designed to smooth, based on vertex normals. The only drawback is that the surface is not perfectly smoothed across patch boundaries and can look a bit inflated.

All Tessellations Schemes are now adaptive mitigating the cost on a per patch basis of all tessellated meshes.

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TESSELLATION

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TESSELLATION

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TressFX HAIR TECHNOLOGY IN THE RUBY DEMO


RUBY HAIR | TressFX

Realistic hair rendering and simulation

– Also used in Tomb Raider

– Goes beyond simple shells and fins representation used in games

– Hair is rendered as actual strands with self shadowing, antialiasing and transparency

– Physical simulation using GPU compute shadersVery flexible to allow for different hair styles and different conditions


RUBY HAIR RENDERING | TressFX

What goes into good hair?

– Anti-aliasing

– Volumetric self shadowing

– Transparency

Thousands of individual hair strands

– Tessellation not necessary

Based on I3D 2012 paper from AMD

“A Framework for Rendering Complex Scattering Effects on Hair”, Yang, et al.

– Algorithms modified for improved real-time performance Anti-Aliasing + Volume Shadows + Transparency


RUBY HAIR RENDERING | TressFX

Kajiya Hair Lighting Model

– Anisotropic hair strand lighting model

– Uses the tangent along the strand instead of the normal for light reflections

– Instead of cos(N, H) , use sin(T,H)

Marschner Model

– Two specular highlightsPrimary light colored highlight shifted towards the tip

Secondary hair colored highlight shifted towards the root


Anti-Aliasing

Every hair strand is anti-aliased manually

–Not using Hardware MSAA!

Compute pixel coverage on edges of hair strands and convert it to an alpha value


RUBY HAIR RENDERING | TressFX Self Shadowing

Self Shadowing

– Uses a simplified Deep Shadow Map technique

No Self Shadows With Self Shadows


RUBY HAIR RENDERING | TressFX Transparency

Order Independent Transparency (OIT) using a Per-Pixel Linked Lists (PPLL)

– Fragments are stored in link lists on the GPU Nearest K fragments are sorted and used for rendering

No Transparency With Transparency


TressFX HAIR SIMULATION IN THE RUBY DEMO


Hair strand is represented as polylines with vertices and edges

LC(Length constraints) is for inextensible hair.

Efficient global and local shape constraints to simulate various hair styles

GSC(Global shape constraints) help preserve hair style and initial shape

– It can guarantee that initial hair style can be restored even after strong agitations

LSC(Local shape constraints)

– For bending/twisting forces to support various hair styles i.e. straight, curly or wavy

Stable time integration with Verlet method

Collision detection and response between hair and model using capsules

RUBY HAIR SIMULATION | TressFX Physics Simulation


The most difficult part of simulation was to figure out how to simulate stylized hair.

In other words, how to hold curly hair shape?

To do it, bending and twisting forces are crucial.

As in robotics, an open-chain structure has joints and each joint has parent-child relationships to its connected joints.

With local transforms in chain structure, we can get a global transform

We find goal positions using local/global transforms for each

vertex and update vertex position by interpolating it using

stiffness value.



Hair can be assigned to the different groups

– Allows different simulation parameters such as stiffness and damping

Fine tuning mechanism for users

– Various hair conditions can be simulated such as wet or heavy on the fly

A simple aerodynamics for wind

All simulation is processed inside GPU using Compute Shader in DX11

Mixed hair vertex and strand level parallel processes utilize GPU architecture efficiently.

By combining with vertex instancing, the actual simulated number of hair can be lower – guide hairs


dry wet


Xuan Yu, Jason C. Yang, Justin Hensley, Takahiro Harada, and Jingyi Yu, A Framework for Rendering Complex Scattering Effects on Hair, I3D 2012.

Dongsoo Han and Takahiro Harada, Real-time Hair Simulation with Efficient Hair Style Preservation, VRIPHYS 2012 .

J. Kajiya and T. Kay. Rendering Fur with Three Dimensional Textures, SIGGRAPH 89 Conference Proceedings, pp 271-280, 1989

Stephen R. Marshner, Henrik Wann Jensen, Mike Cammarano, Steve Worley, and Pat Hanrahan, Light Scattering from Human Hair Fibers, In Proceedings of SIGGRAPH 2003.

TressFX rendering implementation by Karl Hillesdale, Research Engineer, AMD.

REFERENCES


ADDITIONAL REFERENCES

. Hayward, K, "Reflections with Billboard Imposters", http://graphicsrunner.blogspot.de/2008/04/reflections-with-billboard-impostors.html

. Huang, X. "Think DirectX11 Tessellation! Lots of Options", GDC 2010 (link: http://www.microsoft.com/en-us/download/details.aspx?id=27397 (batch link together with tittle name)) . BEHC "Box Projected Cubemap Environment Mapping" , http://www.gamedev.net/topic/568829-box-projected-cubemap-environment-mapping/

. McDonald, J. "Tessellation on Any Budget", GDC 2011 (http://developer.amd.com/wordpress/media/2012/10/Tessellation_On_Any_Budget-GDC2011.pps)

. Kasyan, N. , Schulz, N., Sousa, T. "Secrets of the CryENGINE 3 Graphics Technology", Siggraph 2011 (link: http://www.crytek.com/download/S2011_SecretsCryENGINE3Tech.ppt)

. Lagarde, S. "Local Image Based Lighting With Parallax Corrected Cubemaps", Siggraph 2012 (link: http://seblagarde.wordpress.com/2012/11/28/siggraph-2012-talk/)

. Sousa, T. , Wenzel, C. , Raine, C. "The Rendering Technologies of Crysis 3", GDC 2013

http://graphicsrunner.blogspot.de/2008/04/reflections-with-billboard-impostors.html

http://www.microsoft.com/en-us/download/details.aspx?id=27397

http://www.gamedev.net/topic/568829-box-projected-cubemap-environment-mapping/

http://developer.amd.com/wordpress/media/2012/10/Tessellation_On_Any_Budget-GDC2011.pps

http://www.crytek.com/download/S2011_SecretsCryENGINE3Tech.ppt

http://seblagarde.wordpress.com/2012/11/28/siggraph-2012-talk/


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HOW CRYENGINE 3 AND AMD GCN ARCHITECTURE GAVE BIRTH TO A RED GEM: "PROJECT PHOENIX" Bill Bilodeau Developer Relations Engineer AMD Kedhrin Gonzalez Creative