Blender for XNA

1. Blender for XNA Levi D. Smith @GaTechGrad March 2013

2. Professional Use • Can Blender be used for professional quality graphics? • Elephants Dream (2006) http://www.youtube.com/watch?v=TLkA0RELQ1g • Big Buck Bunny (2008) http://www.youtube.com/watch?v=YE7VzlLtp-4 • Sintel (2010) http://www.youtube.com/watch?v=eRsGyueVLvQ • Tears of Steel (2012) http://www.youtube.com/watch?v=R6MlUcmOul8

3. Views • Selecting the view • Numpad 7: Top View • Numpad 1: Front View • Numpad 3: Right Side View • Numpad 5: Orthographic (see gridlines) • Ctrl + Numpad: Other side (bottom, back, left side) • Note: All commands are for Blender 2.6

4. Cameras • Numpad 0: Camera view • Helpful for positioning view • Ctrl + 0 select camera when using multiple cameras • Right click on line between panes to split screen • Multiple concurrent views of scene • F12 renders the current scene • F3 saves image

5. Modes • Change modes with Tab • Object mode • Lock location and size for XNA • Location: (0, 0, 0) Size: (1, 1, 1) • Vertex coordinates in XNA are relative to orange anchor dot • Edit mode • Select vertices, edges, faces • Move (translate), rotate, scale

6. Creating an Object • A – Select All / Select None • B – Box select • E – Extrude • X – Delete • These can be applied to vertices, edges, and faces • Ctrl + Mouse button – free select • Z – fill object; select only one side

7. Modifying the Object • G – Translate (move) • R – Rotate • S – Scale • Follow operator by X, Y, or Z to lock movement to that axis • Follow operator by number to translate, rotate, or scale by that value

8. Armature • Add a bone to your object • Select point on bone in edit mode and extrude to add new bones • Make sure your bones are aligned with your object • In object mode, select armature and object • Ctrl + P, with automatic weights to assign armature to object

9. Weight Paint • Select mesh in object mode, then select Weight Paint mode • Used for finer control of assigning vertices to bones • Change selected bone in object browser

10. Posing • Pose mode to move armature • Must have armature selected to enter Pose mode • Record button - automatic keyframing • Not recommended • Dope sheet / action editor • I, LockRotScale – insert keyframe • Must be in Pose mode! • Make sure all bones are selected (A) • Can duplicate keyframe using select then Shift + D

11. Animation • Walk cycle • Ctrl + F12 to render images • Images stored in “Output” folder (default C:\tmp) • Select “RGBA” to keep transparency

12. Render a Face • Start with default Cube • Subsurf modifier • High value for CG image, low value for objects to be rendered in real time (games) • Ctrl + R – Loop cut • Mirror modifier • Delete half of the object • Proportional Editing Tool – O Key

13. Render a Body • Set background images as a guide • Export FBX for XNA • Blender Z Up coordinate system • XNA Y Up coordinate system • Rotate 90 degrees on import • Both use “Right Hand Rule” • Select “XNA Strict Options” • Skinned Model Processor • Many models will cause slowdown • Hardware Instancing to draw multiple models efficiently

14. Other Useful Options • F – Make face from selected vertices • 3 or 4 selected vertices only • Remove doubles (button) • Change merge threshold if no vertices are removed • Vertices to be merged must be selected • Shift + D – duplicate object (or vertices/faces) • Ctrl + J – join two objects • Alt + F – fill (generate triangle faces for selected vertices) • Ctrl + T – generate triangles faces from quad faces

15. Texture Mapping • Split View • Change new pane to UV/Image Editor • UV Pane: Image > Open Image > Select your texture • View Pane: Face Select Mode, then select faces • View Pane: Mesh > UV Unwrap > Select unwrap method • UV Pane: Scale and position vertices on texture • Select Texture tab • Set Type to “Image or Movie”

16. Texture Mapping continued • Texture Tab: Under Image, select open and select the texture used • Texture Tab: Under Mapping, select “UV” for coordinates • Texture Tab: Under Mapping, select “UVMap” for map • Press F12 to render the scene and the image should be correctly mapped onto the model • Select specific faces in the View pane to see the corresponding points in the UV Pane

17. Importing into XNA • Default Model object will handle non-moving models • Texture must be imported separately • SkinnedModelProcessor must be created to import animation data • XNA will only use first animation defined in an FBX model

18. DepthStencilState • Be sure to set to default when displaying models after displaying sprites

19. Special Techniques • Billboarding • Keeps flat objects facing towards the camera • Trees in a racing game • Text in a 3D world • Atlas Mapping • Render many similar objects at once • Allows object texture changing without sacrificing processing time

20. What Else Can Blender Do • Particle Systems • Fluid Simulation

21. Sites to Check Out • Blender 3D: Noob to Pro • Free online wiki book • http://en.wikibooks.org/wiki/Blender_3D:_Noob_to_Pro • Diabolical The Shooter – John C Brown • Game developed using Blender models, with guides and tutorials • http://blog.diabolicalgame.co.uk/ • Blasting Bits • My game using Blender models, with development process documented • https://blastingbits.wordpress.com/

22. Books • Foundation Blender Compositing • Author: Roger Wickes • http://www.amazon.com/Foundation-Blender-Compositing-Roger-Wickes/dp/1430219769 • Covers Blender 2.4, before user interface changes