CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
CSc 165
Computer Game Architecture
10(a) – 3D Modeling
for Games
Overview
•
Model Characteristics
•
3D Model File Formats
•
Model Loaders
•
Digital Content Creation (DCC) Tools
•
Skinning and UV-unwrapping
2
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Models
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Static Data
o
o
o
3D geometry (vertex data)
Polygon (face) data
Rendering attributes
o
o
o
Wireframe / Faceted / Smooth-shaded
Lighting & Materials
Texturing (“skinning”) data
Animation Data (sometimes)
o
o
o
Model structure (skeletons, joints)
Model poses
Animation sequences
o walk / run / jump / die …
3
4
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Common 3D Model File Formats
.3ds – 3D Studio Max format
.blend – Blender format
.dae – COLLADA Digital Asset Exchange format
.dem – USGS Standard for Digital Elevation Models
.dxf – Autodesk's AutoCAD format
.hdf – Hierarchical Data Format
.iges – Initial Graphics Exchange Specification
.iv – Open Inventor File Format Info
.lwlo, .lwob & .lwsc – Lightwave 3D file formats
.md2/.md3/.md4/.md5 – Quake Model Files
.ms3d – Milkshape 3D binary format
5
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
.msdl – Manchester Scene Description Language
.nff & .enff – (Extended) Neutral File Format
.obj – Alias|Wavefront Object Files
.off – 3D mesh Object File Format
.oogl – Object Oriented Graphics Library
.ply – Stanford Scanning Repository format
.pov – Persistence of Vision ray-tracer
.qd3d – Apple's QuickDraw 3D metafile format
.viz – used by Division's dVS/dVISE
.vrml – Virtual Reality Modeling Language
.x – Microsoft’s DirectX/Direct3D file format
.x3d – eXtensible 3D XML-based scene description format
See wikipedia – list of file formats
6
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
.OBJ Example
.OBJ File Commands
Grouping
Vertex data
o
o
o
o
o
o
o
o
v – geometric data
vt – texture data
vn – vertex normals
Elements
o
# File: ‘cube.obj’
# This file uses “OBJ” format to define a cube which has a
# different “material” applied to each of its faces.
o
o
o
g – group name
s – smoothing group
mg – merging group
o – object name
# Define 8 cube vertices
v -1.0 -1.0 -1.0
v -1.0 -1.0
1.0
v -1.0
1.0 -1.0
v -1.0
1.0
1.0
v
1.0 -1.0 -1.0
v
1.0 -1.0
1.0
v
1.0
1.0 -1.0
v
1.0
1.0
1.0
Render Attributes
p – point
l – line
f – face
curv – curve
surf – surface
o
o
o
o
usemtl – material name
mtllib – material file name
lod – level of detail
shadow_obj – shadow casting
# Specify the file (library) containing materials
mtllib cube.mtl
#continued...
7
8
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
.OBJ Example (cont.)
OBJ Face/Vertex Data Structures
# file ‘cube.obj’ (cont.)
# Define a group (g) and material for each face (f)
Faces
g front
usemtl red
f 2 6 8 4
# File ‘cube.obj’
v -1.0 -1.0 -1.0
v -1.0 -1.0
1.0
v -1.0
1.0 -1.0
...
f 2 4 3 1
f 2 1 5 6
...
g back
usemtl blue
f 1 3 7 5
g right
usemtl green
f 6 5 7 8
g top
usemtl yellow
f 4 8 7 3
g left
usemtl magenta
f 2 4 3 1
1
2
3
9
V1
V2
V3
V4
V1
V2
V3
V4
1
x y z
2
x y z
3
x y z
4
x y z
5
x y z
6
x y z
...
g bottom
usemtl cyan
f 2 1 5 6
#end of ‘cube.obj’
Vertices
V1
V2
V3
V4
10
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Example: .OBJ Content Loader
Content Loaders
public class OBJLoader implements IModelLoader
{
// Receives a String that specifies a file containing a WaveFront OBJ file.
// Reads the OBJ file and returns a corresponding “TriMesh” object.
Object in some
specific file format
<<interface>>
IModelLoader
Leaf
Scenegraph
+ loadModel(fileName)
Model
File
TriMesh
Read
Content
Loader
Create
- vertexBuffer
- colorBuffer
- indexBuffer
...
Insert
Format-specific
loader code
11
}
public TriMesh loadModel(String modelFilename)
{
TriMesh theModel = new TriMesh();
BufferedReader br = null ;
//get a BufferedReader wrapping the file
try
{ br = new BufferedReader(new FileReader(modelFilename));
} catch (FileNotFoundException e)
{ throw new RuntimeException("FileNotFound: '" + modelFilename + "'");
}
String inputLine = br.readLine();
while ( inputLine != null)
{ switch (getCommand(inputLine))
{
case “v ”: addVertex( inputLine,theModel);
break;
case “vt”: addTextureCoord(inputLine,theModel);
break;
case “vn”: addNormal(inputLine,theModel);
break;
case “f”: addFace(inputLine,theModel);
break;
case “mtllib”: processMaterialLibCommand(inputLine); break;
case “usemtl”: processUseMaterialCommand (inputLine); break;
...
}
inputLine = br.readLine();
}
...code here to do OBJ-specific post-processing to finalize the TriMesh
return theModel;
}
12
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Using A Content Loader
/** This class shows how a Game loads external model files */
public class UserGame extends BaseGame
{
Group rootNode ;
Digital Content Creation (DCC) Tools
Too much work to do “by hand”
//root of scenegraph
...
protected void initGame()
DCC
{ rootNode = new Group (“rootNode”);
commands
Model
File
Model in different format 1
Model
File
Model in different format 2
Tool
...
OBJLoader loader = new OBJLoader();
TriMesh badGuy = loader.loadModel(“badGuyModel.obj”);
“Import”
“Export”
badGuy.updateLocalBound();
Scenegraph
rootNode.addChild(badGuy);
...code here to add other objects to the scenegraph...
}
...
rootNode.updateGeometricState (0, true);
Model
File
//init xforms and BV’s
Content
Loader
TriMesh
}
Model in Content-Loader format
13
14
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Blender
DCC Tools
Features:
 Modeling, texturing, lighting, UV-mapping
Commercial
o
o
o
o
 Animation rigging/skinning
Maya
3DStudio Max
Lightwave
etc., etc. …
 Particle, physics, soft-body, fluid & cloth simulations
 Game engine, video post-processing
 Python scripting/plugin support
 Cross-platform (Windows, Linux, Mac OSX, FreeBSD, Solaris….)
 Import/export for a wide variety of model file formats
 Extensive online documentation/wiki support
Free (or nearly)
o
o
o
o
Availability:
Blender
MilkShape3D
Maya / 3DStudio Max for students
etc. …
 Free (GNU GPL license), at http://www.blender.org
Tutorials:

http://www.blender.org/support/tutorials
15
16
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Basic Blender Controls
Example Blender Models
Viewing:
Object Manipulation (in object mode):
•
Scroll-wheel: zoom
•
RMB: select (SHIFT to add)
•
MMB: orbit (rotate 3D view)
•
A-key: toggle select-All
•
Shift-MMB: pan
•
•
Reset view to
B-key: activate border-selection
(rubber-band select)
•
DEL-key: delete selected
•
Z-key: toggle wireframe
•
LMB: position 3D cursor
•
NUM-0: switch to camera view
•
Shift-A: add object (at cursor loc)
•
NUM-5: toggle ortho/perspective view
•
Transform selection:
•
HOME: set view to show all objects
•
Ctrl-Z: undo
•
Ctrl-S: save workspace
•
Ctrl-N: reset (discard all; new session)
•
F12: render
Top: NUM-7 Front: NUM-1 Side: NUM-3
17
R-key: rotate S-key: scale G-key: grab
LMB to accept; RMB or ESC to cancel
18
•
Quick move: RMB on object, drag,
LMB to drop
•
Shift-D: duplicate selection
(drag to reposition)
•
TAB: toggle object/edit mode
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Model Exporting
Building Models From Primitives
Most DCC tools export a variety of formats
Original Cube
Extrude
Blender supports exporting to:
o Collada XML (“.dae”)
o Wavefront OBJ (“.obj”)
o Stanford Graphics Library (“.ply”)
o 3DStudio Max (“.3ds”)
o A host of others via “addons”
Multiple Extrusions
 Including “OgreXML”
Sage has ModelLoaders for
Scale Ends
Model concept: The Essential Blender,
Roland Hess, Blender Foundation
o
Add Bevels
and Smooth
Scale Inner
Surfaces
o
OBJ
OgreXML
19
20
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Advanced Modeling: Sculpting
Exporting Models
# Blender3D v249 OBJ File:
CrossDemo.blend
# www.blender3d.org
mtllib CrossDemo.mtl
v 0.515410 2.745096 -0.496360
v 0.515410 2.745096 0.496359
v -0.477309 2.745096 0.496359
v -0.477309 2.745096 -0.496360
v 0.515410 3.737815 -0.496359
v 0.515410 3.737815 0.496360
v -0.477309 3.737815 0.496359
v -0.477309 3.737815 -0.496360
v -0.523100 6.135959 0.542150
v -0.523100 6.135958 -0.542150
v 0.561200 6.135959 0.542150
v 0.561201 6.135958 -0.542150
Export:
Ogre
OBJ
DAE
Original sphere
“Add” brush
applied to Sphere
“Grab” brush
...#total 44 vertices
usemtl Material
s 1
f 2 6 7 3
f 5 1 4 8
f 12 10 9 11
f 13 14 15 16
f 1 42 44 4
f 42 21 24 44
...#total 42 faces
21
“Layer” brush
“Inflate” brush
Images from: The Essential Blender,
Roland Hess, Blender Foundation
22
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
“Texture” brush
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Texture Space Subdivision
Skinning
Applying “texture” to 3D models
Texturing meshes by dividing texture space:
Problem: texture mapping is per-polygon:
Models are collections of polygons
Texture Map
Polygon Mesh
(1,1)
Polygon
Texture Map
v
(0,0)
v
u
u
23
24
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Texture Subdivision Difficulties
Skinning Example
Requires creating a complex mapping
(and the model is often curved)
 How do we create the texture map?
 How do we determine the correct mapping?
Mapping texture locations
to model coordinates
Image credit: Practical Java Game Programming,
Clingman et.al., Charles River Media
Image credit: Practical Java Game Programming,
Clingman et.al., Charles River Media
25
26
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Creating Texture Skins
 Create the model
Example: Soup Can
GIMP, PhotoShop, …
Soup Can Model
(Cylinder)
 Flatten the model (“UV Unwrapping”)
Mark seams
Create
Texture
Image
Unwrap
Cut along seams (“project”)
 Save unwrapped (flattened) UV image
 Save model with texture coordinates
Model with Texture Coords
 Use UV image as a “pattern” to create tex map
Texture Image
Texture
Mapping
GIMP, PhotoShop, ...
 Apply texture map to model
Image credit: 3D Game Programming All In One,
Kenneth Finney, Premier Press
27
28
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Blender UV Unwrapping
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Character Models
More complex, but same approach:
 Create model
 Mark/cut seams (some tools support groups)
 Project UV’s
 Save projection image
 Use projection image to create texture
 Apply texture to UV map/model
29
30
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Blender: Character Example
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Step 2: Mark Seams
Step 1: Load/Create Model
Example from: 3D Game Programming All In One,
Kenneth Finney, Premier Press
31
32
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Step 3: Export UVs
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Step 4: Paint Texture
GIMP,
PhotoShop,
MS Paint,
etc.
33
34
CSc 165 Lecture Note Slides
10a - 3D Modeling For Games
Step 5: Apply Texture to Model
35