3d modeling & sketchupcs410/yr2014fa/more_progress/l18_sketchu… · 3d modeling & sketchup...

3D Modeling & Sketchup

Lecture 118, Tuesday October 30th, 2014

SketchUp / SkechUp Pro

10/30/14 ©Bruce A. Draper & J. Ross Beveridge 2014 2

Available to CS 410 students on Windows Machines in USB 110.

Sketchup History


Opening Move


Templates


One Rectangular Face

!  Exact values in the Dimensions Box. !  You will want to learn to enter values here.


Export to .obj format


Export to .obj format

!  Note, this is why we use .obj files.


When Exporting Consider

!  Do you export edges? (generally no) !  Are you two faced? (depends) !  How about only triangles?

!  This is particularly easy with rectangles.

! May be helpful depeding upon your ray tracer design and what you implement.

!  We are not yet ready to say much about texture maps


Add Some Color


Now, 7 things to learn …

!  Canonical Views

!  Rotating Views

!  Zooming Views

!  Extruding a 2D shape to produce 3D shape

!  Selecting parts – faces

!  Painting faces

!  Removing a face


A Perfect Cube


Coloring A Face - How


Delete the Top Face


Scaling


Moving an Object


•  Pay close attention

•  Direction of move is guessed

•  It is indicated in color of axis

•  Changing viewpoing will probably change the defaults

Selection Parts and All


Cloning an Object

!  Hold down the option key while dragging


Cloning Once, Why Not More


Note the magic

“2x”

Make 5 – Select 5 – Repeat = 25


Rotation – This is Trickier


Stonehenge


Stonehenge 2014


Learning More


Modeling Approach #1: Polygonal Meshes (review)

Surface patch = a polygon in 3D !  3 or more vertices !  Each vertex is an (x, y, z) triple !  Vertices are supplied in order

!  Boundary goes from vertex #1 to vertex #2 to … vertex #N, and back to vertex #1

!  All vertices must be co-planar !  Polygon must be convex

10/30/14 ©Bruce A. Draper & J. Ross Beveridge 2014 Slide 25

Surfaces: Connected Polygons (review) !  A mesh surface is then just a set of non-

overlapping polygons that share vertices and edges


Triangle Strip Quad Mesh

http://groups.csail.mit.edu/graphics/classes/6.837/F98/TALecture/

Surfaces are generally not planar (review)

!  Although every polygon in the mesh must be

!  Patches form a locally linear approximation to curved surfaces


3D Model by Daniel Rypl at the Czech Technical University in Prague.

Approach #2: (CFG) Constructive Solid Geometry

!  Modeling language defines shape primitives !  E.g. sphere, cube, pyramid,…

!  Shapes can be transformed !  Translation, Rotation, Scale, …

!  Shapes manipulated as sets !  Shapes can be added (A union B) together !  Shapes can be intersected (A intersect B) !  Shapes can be subtracted (A minus B)


For example


http://commons.wikimedia.org/wiki/File:Csg_tree.png

Intersection

Union

Set Difference

Representing CSG

!  CSG exploits object oriented representations.

!  A “Shape” is a top-level object. !  Each type of shape is a subclass

!  Spheres store an (x,y,z) center and radius. ! Cubes store vertices.

!  All shapes implement transformation operators.


Approach #3: Splines

!  Splines combine 3D surface patches

!  Each surface is a 3rd-order surface patch ! Made from two

3rd-order curves


http://commons.wikimedia.org/wiki/File:NURBS_surface.png

More on curves and surfaces around

Thanksgiving.

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