G-Octave Manual: Drawing Functions
When complete, Goctave will include a very versatile set of drawing
functions, known as the Goctave Drawing Toolkit. These are intended
to work in conjunction with the image manipulation functions included
with Octave, to provide a set of drawing primitives that you can use
in your programs to create simple charts and line drawings.
All functions in this packages are prefaced with "gd_". They have
the general form: image = gd_function(image, color, arg_1, ...,
arg_n), where image is a bitmap contained in a matrix, and color
is an index in the current color map.
The images returned can be displayed with octaves
image() function, or further manipulated. In the future I
would like to write and improved display engine for Octave images.
PROBLEMS/BUGS: Most of these functions are currently
implemented as interpreted Octave files, ergo are quite slow. This is
because I wanted to get the system prototyped and test the algorithms.
Once I have everything working, I will rewrite them in C and we'll see
some serious speed improvements. Of course, help would be appreciated.
- Function File : image = gd_bezier (
image, color, x0, y0,
x1, y1, x2, y2, x3,
y3)
-
Draws a bezier curve on the image in color. Bezier
curves are parametric curves defined by a start point, (x0, y0), an
end point, (x3, y3), and two control points (x1, y1) and (x2, y2).
Inputs:
- image
-
The image to draw upon.
- color
-
The color to use. An index in the current colormap.
- x0...x3, y0...y3
-
The x and y coordinates of four points. See above.
Outputs:
- image
- The new image (with the curve drawn on it).
- Function File : image = gd_bezier (
image, color, x0, y0,
x1, y1, x2, y2, x3,
y3)
-
Draws a bezier curve on the image in color. Bezier
curves are parametric curves defined by a start point, (x0, y0), an
end point, (x3, y3), and two control points (x1, y1) and (x2, y2).
Inputs:
- image
-
The image to draw upon.
- color
-
The color to use. An index in the current colormap.
- x0...x3, y0...y3
-
The x and y coordinates of four points. See above.
Outputs:
- image
- The new image (with the curve drawn on it).
- Function File : image = gd_segment (
image, color, x0, y0,
x1, y1)
-
Draws a line segment on the image.
Inputs:
- image
-
The image to draw upon.
- color
-
The color to use. An index in the current colormap.
- (x0, y0), (x1, y1)
-
The x and y coordinates of the end points.
Outputs:
- image
- The new image (with the line-segment drawn on it).
This Document is Copyright 2000 By Kevin Straight.
Permission is hereby granted to make verbatim copies for non-profit
purposes.