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Rendering a static scene with lighting and shading is a complex
program. I have written one as have some of you.
The basic input is a 3D model.
A 3D model must have coordinates of vertices.
The model may have lines, polygons and more complex
shapes and imported objects. There may be colors, lighting
and texture mapping. A number of programs are available to
allow a person to create or enter a model.
There are many formats for 3D models.
I have shown the Utah Graphics .dat (ASCII) and .det (binary) files
that have vertices and polygons. There is also .stl and UCD .inp that
have key words and syntax (ASCII) and there are many more formats.
cube.dat
cube2.stl
ucd1.inp
One primitive scene input, to a renderer named "run6" looks like
lab6_input1
The model is your "world" that is to be rendered.
The world does not move, the point of view, your eye, moves.
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OpenGL is a 3D rendering system. It uses what is called a
"rendering pipeline" to present the 3D modeled scene as a 2D
image on the computer screen.
Graphics cards may have some to very sophisticated rendering
built into hardware and software.
Your 3D world model may use only triangles to represent
the surface of objects. Triangles are convenient for
renderers because the three points that define the triangle
exactly define a plane. Everywhere on that plane has the
same normal vector that is needed in computing the lighting.
Use of quadrilaterals and higher order polygons, may not
be planar. Thus, every point on the surface may have a
unique normal vector, that must be computed, to determine
the lighting.
Covered in the textbook, Chapter 12, is Advanced Rendering.
This covers ray tracing and other advanced techniques.
For download of a ray trace renderer, the one I like best is
www.povray.org and www.povray.org/download
Available for MS Windows, Linux, MacOS in both binary and source.
Example outputs:
features
scene description
For shadows, light through glass, rainbow effects, it is best
to use a ray casting renderer.
For very complex geometries without the above effects, a
Z-Plane renderer may be best. For example, OpenGL can do
shadows, yet they are difficult.
The next level of complexity and sophistication is rendering
animation. This is typically done off line by massive computing
power. We have seen some trailers of some 3D cartoon movies.
Technical activities also need animation.
Dynamic rendering, international space station assembly
A different animation than shown previously.
matlab sample plots
helix.m source code
hump.m source code
hump_m.out plot data
hump2.m source code
hump2_m.out plot data
hump3.m source code
hump3_m.out plot data
surfplot.m source code
surfplot_m.out plot data
shape22.m source code
shape22_m.out plot data
See Google Sketchup for 3D object and scene input.
Cartoons and games are rendering every frame.
Special techniques are used to obtain the required frame rates.
Each frame must be rendered or at a minimum, the pixels that
change must be rendered.
We have java programs to display .dat and .stl files in 3D
light_dat.java
light_dat1.java rotated hump2.dat
light_normal.java
datread.java
light_stl.java
light_normal_stl.java
heapsort.java
Think outside the cube.
Consider the fourth dimension, not time.
Is the video consistent?
tetraspace.alkaline.org
forward link to 4D in lecture 21
time to do HW5
To make 3D physical objects, render 2D and cut out.
Leave tabs when cutting, if you are going to glue together.
dodecahedron.java
The regular polyhedra have vertex on a sphere:
dodecahedron.py3 source code
icosahedron.py3 source code
tetrahedron.py3 source code
cube.py3 source code
octahedron.dat no source code needed
Example of another hump, 2D, 3D, then scale and make .stl
humpc.java source code
humpc_java.out output
humpc2.dat 2D with lines
humpc.dat 3D with triangles
humpcc.dat rotated and with colors in light_dat.java
humpc30.stl scaled .stl
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Many web sites on Java GUI, AWT, Swing, etc.
Many web sites on Python wx, tk, qt, etc.