Integrating Multi-Resolution Meshes Into Games - GDC '99 Multi-Resolution Mesh in Dark Reign II March 18, 1999 *All trademarks and brands property of their respective owners Integrating Multi-Resolution Meshes Into Games - GDC '99 Who are we? Pandemic Studios Pandemic Studios Developing Dark Reign II and Battlezone 2 Dark Reign II Dark Reign II Sequel to popular RTS Game John Cooke 3D Programmer Dark Reign II Rick Glenn Art Director Dark Reign II Integrating Multi-Resolution Meshes Into Games - GDC '99 Stay Traditional Real Time Strategy Stay Traditional Real Time Strategy Base Building, Resource Management, Big Battles Dark Reign II Design Philosophy Integrating Multi-Resolution Meshes Into Games - GDC '99 True 3D True 3D Player controlled camera True Scale Night/Day Physics Infantry based Infantry based Detailed units and animations Fifa-style Dark Reign II Design Philosophy Integrating Multi-Resolution Meshes Into Games - GDC '99 RTS means lots of units RTS means large views Detailed infantry means tons of polys Pentium 550 with Voodoo 3 minimum The Problem Integrating Multi-Resolution Meshes Into Games - GDC '99 Static LOD Static LOD The way weve always done it Tessellation Tessellation Messiah Multi-Resolution Mesh (MRM) Multi-Resolution Mesh (MRM) IALs latest 3D software technology Searching for a solution Integrating Multi-Resolution Meshes Into Games - GDC '99 MRM allows SMOOTH real time polygon reduction of meshes. What is MRM Integrating Multi-Resolution Meshes Into Games - GDC '99 Scalability Scalability -real time frame rate control via polygon reduction. Visual quality Visual quality -increase foreground detail by reducing background. -better in game engine cut scenes. Why use MRM? Integrating Multi-Resolution Meshes Into Games - GDC '99 Flexibility - -author only once for each unit - -tweak unit counts - -generate static LODs MultiRes* Software Toolkit consists of: - -MRMGEN.dll: integrate into authoring tool. - -MRM plug in for MAX: generates MRM files. MRM data from an export file Why use MRM? Integrating Multi-Resolution Meshes Into Games - GDC '99 MRM runtime is very simple. - -No run time tesselation or data generation of any kind. All mesh data is pre-allocated. - -Data describes how faces should re-index their vertex data to display a mesh at various resolutions. - -Easy to integrate with any graphics engines mesh data format. Integration into Code Integrating Multi-Resolution Meshes Into Games - GDC '99 MRMGEN does a lot of complex decision making to generate the runtime data - -Integration programmer doesn't need to know how it works. - -It uses only the meshes original data, determining the least important vertex at each resolution level. - -It attempts to keep texture and normal distortions to a minimum for as long as possible. Integration into Code Integrating Multi-Resolution Meshes Into Games - GDC '99 Works best with a continuous skin, but not absolutely necessary. - -MRMGEN doesnt accept data from multiple meshes. - -MultiRes Modifier plugin generates MRM files directly from Max. - -MultiRes Software Toolkit provides code for loading and saving MRM data. Integration into Code Integrating Multi-Resolution Meshes Into Games - GDC '99 Write a simple mesh viewer application with your graphics library for development. - -Integrate the MRMGEN.dll directly into the tool and generate custom file format including MRM data. - -Provides artists a quick and easy way to see their assets in the game. Tool Integration Integrating Multi-Resolution Meshes Into Games - GDC '99 Integration is easier for continuous- skin mesh data structures - -Continuous-skin, envelope animated models are typical for most current games - -Only requirement is vertex and face data must exist in contiguous arrays - -Meshes have separate arrays of vertex positions, normals, texture coordinates, and faces - -Each face has 3 sets of indexes; 1 each for vertex position, normal, and texture uv - -Could use other formats i.e. 1-to-1 mapping for vertex, normal, and uv - -IMESH accepts custom data records and keeps track of them for you. Data structures Integrating Multi-Resolution Meshes Into Games - GDC '99 MRMGEN generates MRM update records and optimizes the mesh - -One Vertex Update Record for each vertex in the mesh. - -Each contains a number of faces to increase/decrease and a collection of Face Update Records. - -One Face Update for each face vertex attribute to change: position, normal, uv. Data structures Integrating Multi-Resolution Meshes Into Games - GDC '99 Data Structures typedef struct MRMUpdatesTag { unsigned longmaxNumVertices; unsigned longmaxNumFaces; unsigned longmaxNumNormals; unsigned longmaxNumTexCoords; VertexUpdate *vertexUpdates;// one for each vertex in the mesh } MRMUpdates; Integrating Multi-Resolution Meshes Into Games - GDC '99 Data Structures typedef struct VertexUpdateTag { unsigned longvertexIndex; unsigned longparentVertexIndex; unsigned longnumNewFaces; unsigned longnumNewNormals; unsigned longnumNewTexCoords; unsigned longnumFaceUpdates; FaceUpdate *faceUpdates;// typically 2 } VertexUpdate; Integrating Multi-Resolution Meshes Into Games - GDC '99 Data Structures typedef struct FaceUpdateTag { unsigned long faceIndex; AttribTokenattrib;// Vertex, Normal, or TexCoord Unsigned longvalue[2];// New attrib index; Increasing or Decreasing } FaceUpdate; Integrating Multi-Resolution Meshes Into Games - GDC '99 Resolution change is achieved by traversing the update records. - -Only records for the vertices being removed or added are looped - -Vertex data is sorted by decreasing order of importance so LOD changes are minimal hit on the cache. - -Important as mesh polygon count increase - -MRM data is typically about the same size as the mesh data itself. Data structures Integrating Multi-Resolution Meshes Into Games - GDC '99 Distance from the camera is a good primary polygon reduction metric - -Since detail is wasted in the background, get rid of it. - -Increase your polygon budget for the foreground, or for more units, effects, etc. - -Frame rate is another great metric - -Extra reduction for when frame rate drops below threshold. Runtime Integrating Multi-Resolution Meshes Into Games - GDC '99 Digimation MultiRes tools for 3DS Max. - -3DS plug-in lets artists hand tweak MRM parameters and see the results in real-time. - -Dialogs for: -Vertex Merging Threshold: merge vertices of distinct groups; MRMGEN optimizes mesh. -Maintain Base Vertices: maintains vertices selected when MRMGEN is invoked. -Boundary Metric: keep materials distinct at the expense of reduction. - -Multiple Normals per Vertex with Crease Angle specification. - -Gives programmers an instant game friendly format and code toolkit. 3DSMax* vs. Softimage* Integrating Multi-Resolution Meshes Into Games - GDC '99 For Softimage you need to write your own plug-in or custom tool. Dark Reign II uses a custom tool along with some versatile tricks Frog Pose 3DSMax vs. Softimage Integrating Multi-Resolution Meshes Into Games - GDC '99 MRM allows for better art MRM saves time More Time = More Art MRM gives peace of mind Production Application Integrating Multi-Resolution Meshes Into Games - GDC '99 Shoot for a higher ideal Can think about the high end Less low end issues than with Static LODs Concept Integrating Multi-Resolution Meshes Into Games - GDC '99 One Time Authorship of Assets One High poly rather than several Low poly Animate one model Dont have to deal with transfer of animations Author Once Integrating Multi-Resolution Meshes Into Games - GDC '99 Dark Reign II Unit created at 800 polys Time to create unit = 1 Day Integrating Multi-Resolution Meshes Into Games - GDC '99 Interstate 76 Car at 300 Polys Time to create car = 1 Day Integrating Multi-Resolution Meshes Into Games - GDC '99 Static LODs then created at 200, 100, and 75 polys Time to create static LODs= 1 Day Integrating Multi-Resolution Meshes Into Games - GDC '99 Dark Reign II assets MRMd to 800, 500, 300 polys Time to create Continuous LODs = 0 days Integrating Multi-Resolution Meshes Into Games - GDC '99 Art team can create two MRMd assets in time it takes to create one asset using static LODs Integrating Multi-Resolution Meshes Into Games - GDC ' poly model 800 poly model How does number of polys in source model affect MRMing? Integrating Multi-Resolution Meshes Into Games - GDC ' poly source 800 poly source Both models at 800 polys Integrating Multi-Resolution Meshes Into Games - GDC ' poly source 800 poly source Both models at 500 polys Integrating Multi-Resolution Meshes Into Games - GDC ' poly source 800 poly source Both models at 300 polys Result - No penalty for Higher Source Model Integrating Multi-Resolution Meshes Into Games - GDC '99 Less production time Able to experiment more No popping Easier to change an asset Dial-In MRMing on a per asset basis Better Than Static LODs Integrating Multi-Resolution Meshes Into Games - GDC '99 Code rarely optimized early on Lack of static LODs early on How many times do you run the game Easier to experiment Better Frame Rate During Production Integrating Multi-Resolution Meshes Into Games - GDC '99 Proven technology Trying to project ahead to system spec is difficult 1 to 2 years before release High visuals vs Frame rate Take a lot of risk in production Its usually pretty late in the production when you decide to either reduce polys or optimize engine Peace of Mind Integrating Multi-Resolution Meshes Into Games - GDC '99 Low end versus high end Low end = 166 with Voodoo 1 High end = 550+ with TNT2+ How do we make a great game for all systems Bigger Sweet Spot Integrating Multi-Resolution Meshes Into Games - GDC '99 Art made higher than intended target Game will look better as machines get faster Longer Legs Integrating Multi-Resolution Meshes Into Games - GDC '99 Fewer texture and normal discontinuities is better for MRM Mesh is more efficient with fewer discontinuities Trade off between discontinuities and efficient use of texture space Art Considerations Integrating Multi-Resolution Meshes Into Games - GDC '99 Why do we like MRM Why do we like MRM easy to use increases frame rate without degrading visual quality. Who can use MRM Who can use MRM anyone writing a 3D game that displays significant perspective reduction. i.e. everybody! Is MRM right for you Integrating Multi-Resolution Meshes Into Games - GDC '99 Things to consider when considering using MRM in your project Things to consider when considering using MRM in your project how else are you going to compete in the brave new world of super-scalability Is MRM right for you