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Dragon Age II DX11 Technology

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  1. Dragon Age II DX11 Technology Andreas Papathanasis BioWare

  2. Sequel to the successful RPG Dragon Age: Origins • Focus on combat, magic, cinematics • Rebooted Art Style, focus on Graphics technology • Out next week on PC / Xbox 360 / PS3

  3. Our pitch for DX11 technology We discussed within our project tiered options for taking advantage of next generation PC GPUs: • Tier 0: DX9 with very high quality shaders • Tier 1: Basic DX11 integration • No compute or tessellation shaders • Takes advantage of shader models 4 and 5 • Tier 2: Typical DX11 integration • Computeand tessellation shaders fully supported • Tier 3: Advanced DX11 integration • Multithreading • Requires significant refactoring of the higher level engine

  4. Why DirectX 11? • Opportunities to integrate well documented, impactful visual features using SM4/SM5, new shader stages • Guaranteed feature set (no cap bits) • Great way for programming and art teams to prepare for the next generation • Powerful, evolving debugging tools


  5. GPU PerfStudio 2 – Shader Debugging on DX10/DX11

  6. Why DirectX 11? • Reliable backwards compatibility with older hardware • Customers have the hardware and expect games that use it Steam hardware survey

  7. DirectX 11 features overview • Dynamic lighting • Tessellation • Diffusion Depth of Field • Contact hardening soft shadows

  8. Dynamic Lighting

  9. Dynamic Lighting

  10. Dynamic Lighting • Based on the popular light pre-pass method • http://www.wolfgang-engel.info/blogs/?p=26 • Extra pass to render scene normals • Render all dynamic light spheres to a light buffer • Allows for hundreds of lights • Minimal engineering effort to integrate on DX11: • Multiple render targets work with MSAA • Guaranteed render target format support • Small per-draw overhead on the CPU • Makes a lot of sense for a spell-rich game like Dragon Age II Light buffer

  11. Tessellation • Big research focus for the team • Great potential for taking geometric detail to the next level • Lends itself to LOD naturally, without affecting CPU or complicating the engine codebase

  12. Tessellation challenges • Piecewise level construction • can cause gaps between adjacent objects when normals don’t match at the edges • would require content to be redone for DX11 • fell back to parallax mapping techniques for displaced look • ongoing research topic for our next projects • Some content (i.e. characters) is already tessellated at desired density for non DX11 platforms • On Dragon Age II we used tessellation for terrain silhouette smoothing (using PN triangles algorithm)

  13. Tessellation on terrain Without tessellation With tessellation

  14. Tessellation performance • VERY easy to kill performance with excessive tessellation • Performance improvements that made a difference in our engine (sorted in order of the performance win we got): • Only tessellate objects close enough to the camera • LOD in the hull shader • View frustum culling (important for high polygon objects that span a large area, like terrain) • Distance adaptive tessellation factor • Only tessellate objects that will end up being visible (occlusion culling even more relevant if you’re rendering lots of tessellated objects)

  15. Diffusion Depth of Field • Custom multi-pass Diffusion DOF solver • Technique will be described by Holger Gruen later today, and appear in Game Engine Gems 2 • Much higher quality than our DX9 DOF solution, almost as efficient

  16. Diffusion Depth of Field DX9 DOF Diffusion DOF

  17. Diffusion Depth of Field DX9 DOF

  18. Diffusion Depth of Field Diffusion DOF

  19. Contact hardening shadows

  20. Contact hardening shadows • High quality shadow filter • Accelerated by GatherRed/GatherCmpRed Shader Model 5 instructions • Shader source code in the DirectX SDK • Trivial to integrate, great visual quality improvement for directional shadows

  21. Contact hardening shadows Old PCF filter Non uniform contact hardening filter

  22. References • Light pre-pass http://www.wolfgang-engel.info/blogs/?p=26 • PN triangle implementation • June 2010 DirectX SDK, PNTriangles11 sample • Diffusion DOF solver Game Engine Gems 2 (http://www.gameenginegems.net/) • Contact hardening soft shadows • June 2010 DirectX SDK, ContactHardeningShadows11 sample

  23. Conclusion • API and market is mature • Lots of algorithms available that can enhance your particular style of game • Initial investment in DX11 integration should pay off quickly • Hardware vendors can help you

  24. Q & A DirectX 9 DirectX 11 andreas@bioware.com