Blender for XNA

Levi D. Smith@GaTechGrad

March 2013

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

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

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

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

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

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

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

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

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

Animation

• Walk cycle

• Ctrl + F12 to render images

• Images stored in “Output” folder (default C:\tmp)

• Select “RGBA” to keep transparency

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

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

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

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”

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

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

DepthStencilState

• Be sure to set to default when displaying models after displaying sprites

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

What Else Can Blender Do

• Particle Systems

• Fluid Simulation

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/

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