COS 426 Home
Project 1 hints
- First of all, go to the precepts either Mon 8:00pm or
Thu 3:30pm in CS Bldg. 105.
- Next, make use of our office hours
and lab hours.
- Also, you can always send us e-mail or post questions to the newsgroup.
- Check out how to setup your
account to run the COS 426 programs.
- To draw filled triangles, use the simple sweep-line
algorithm for triangles, as described on pp. 3-4 of lecture notes #2.
- To draw filled convex polygons, simply triangulate the
polygon and then draw all the triangles using the code for
- To draw filled concave polygons (extra credit) use the
more complex sweep-line algorithm (pp. 14-16 of lecture notes
#2, or H&B sec 3-11.) for polygons.
- If you wish to implement Gupta-Sproull antialiased lines
for extra credit, there is a good discussion (and some
pseudocode) in Foley, et al.
- To implement the "print" feature, check out this brief
description of postscript.
- Some frequently asked questions:
- How do I set a pixel on the canvas?
- Using dev_set_pixel(x, y).
- Do we have to do any TCL coding?
- For the required part, you don't have to. But
depending on the extra credit options you choose, you
might have to.
- In my.c, some functions have a
vertex_t * parameter. Is this a pointer to
only one vertex or to the beginning of an array of
- It is a pointer to the beginning of an array of
vertices. How many vertices? It depends on the object
(take a look at graphics.h).
- Where should the code for circle rendering go?
- What about circle.c? Don't forget to
add TOOL_CIRCLE cases in app.c,
OBJ_CIRCLE cases in graphics.c, and
circle.c in the source list in the
- How can I debug Tcl code?
- You have to
debug the interpreter that runs the Tcl code. For
example, suppose you want to debug the function
app_click1() in app.c:
/u/you/cs426/1> gdb drawsh
(gdb) b app_click1
% source draw.tcl
- For triangle scan conversion, you don't have to
use Bresenham's algorithm, but you can for extra credit. See
the course newsgroup for a more
- Stay tuned for more...