Displaying 3D ModelsAnnouncementsTriangles are fine, but models are better3D Modeling3D Model formatsModels in XNAModels in XNA (cont’d)Working with Models in XNAImporting Models into Visual StudioLoading Model via Content managerDrawing a ModelMore on ModelsDisplaying 3D ModelsGame Design ExperienceProfessor Jim WhiteheadMarch 4, 2009Creative Commons Attribution 3.0 (Except copyrighted images) creativecommons.org/licenses/by/3.0Announcements• Days until Final Project Due: 12► Due Monday, March 16• 3D modeling homework► Assignment text now on web► Due Monday, March 9► Assignment will involve:• Create a simple 3D model (e.g., in Blender)– Something slightly (but not by much) more complex than a cube will be fine• Make this model show up in XNA• Extra credit for making model rotate, applying bitmap textures• Goal is to exercise a model import pathway► Intended to be a straightforward assignmentTriangles are fine, but models are better• Today’s 3D games have a large number of objects► Theoretically possible to create these objects by manually writing C# code to create each individual triangle► In practice, this is rarely done.► Far better to use a 3D modeling tool• Maya, XSI, 3DS Max, Blender► Allows artists to create objects in world► Allows programmers to focus on behavior of objects► Modeling tools permit much faster creation and editing of models3D Modeling• Several ways to model a 3D object► Polygonal modeling• Objects are subdivided into a series of polygons (triangles)• Can only approximate curved surfaces• Dominant modeling form in computer games and computer graphics due to speed of rendering► NURBS• Surfaces are defined by spline curves• Curves defined and controlled by control points► Splines and patches• Curved lines define surfaces. Between polygons and NURBS► Primitives modeling• Objects built up from primitive shapes (balls, cubes, cylinders, etc.)3D Model formats• There is a huge number of 3D model formats► No dominant standard► Interchange among models is often lossy• XNA supports two 3D model formats► .X (DirectX)► .FBX• Originally for FilmBox by Kaydara, then Alias, now AutodeskModels in XNA• Model► Represents some entity• A person, a car, or potentially a complex scene with many parts► Typically used to represent one logical object (e.g., a person) that has multiple parts (head, arms, legs, etc.)► A model contains multiple meshes and bones• Mesh► Represents a single physical object► Triangles, textures, shaders, etc.► XNA ModelMesh class• Bone► Represents placement of each mesh relative to other meshes► A transformation matrixModelModelMesh1NCarBody +boneWheel +boneDoor +boneBone1NModels in XNA (cont’d)• ModelMesh contains:► List of ModelMeshPart► List of Effects ► Verticies for triangles that comprise this mesh• VertexBuffer► Also has a bounding sphere• ModelMeshPart► Represents a set of triangles that share the same materials (e.g., shader, or Effect)► Has indexes into the ModelMesh► Starting index, number of triangles, number of primitives to use from parent ModelMesh’s VertexBufferModelModelMesh1NBone1NModelMeshPartEffect1N1NVertexBuffer11Verticies1NEffect11StartIndex NumVerticies PrimitiveCount1111Working with Models in XNA• Bring model into XNA project inside Visual Studio• Load model into XNA via Content manager• Draw model by iterating through all contained meshesImporting Models into Visual Studio• Import model into Content directory► Copy .x or .fbx file, along with associated texture images, into Content directory in XNA project► Inside Visual C#, right-click on Content directory• Add… Add Existing Item• Select .x or .fbx file► Similar process to adding bitmap textures, etc.Loading Model via Content manager• Models are loaded via the content manager► Model model = Content.Load<Model>(@”{name of my model without .x or .fbx extension}”)• XNA parses the model file, and fills in verticies, textures, and effects in Model, and ModelMeshes► In XNA, this is a robust operation, big time savings► In many open source 3D game engines, model import can be a big problem► At present, typically is not safe to assume model import will work smoothly in a given 3D game engine► Need to test your tool chainDrawing a Model• Iterate through all of the meshes► Iterate through each effect for each mesh• Set lighting, camera, and world for each effect► Draw each mesh using Draw() method on ModelMesh classforeach (ModelMesh mesh in model.Meshes) {foreach (BasicEffect be in mesh.Effects) {be.EnableDefaultLighting();be.Projection = camera.projection;be.View = camera.view;be.World = world * mesh.ParentBone.Transform;}mesh.Draw();}• Examine example code from Chapter 10 of Learning XNA 3.0More on Models• Explanation of parts of XNA models► http://blogs.msdn.com/shawnhar/archive/2006/11/20/mo
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