Triangle


Martin McBride, 2020-08-26
Tags geometry triangle
Categories generativepy generative art

The Triangle class draws a triangle.

There is also a triangle function that just creates a triangle as a new path.

Triangle class methods

The Triangle class inherits add, fill, stroke, fill_stroke, path, clip and other methods from Shape.

It has additional methods:

  • of_corners

of_corners

Creates a triangle based on a set of 3 points.

of_corners(a, b, c)
Parameter Type Description
a (number, number) (x, y) tuple, giving the position of corner a of the triangle.
b (number, number) (x, y) tuple, giving the position of corner b of the triangle.
c (number, number) (x, y) tuple, giving the position of corner c of the triangle.

triangle function

Adds a triangle as a new path, without the need to create a Triangle object in code.

triangle(ctx, points)
Parameter Type Description
ctx Context The Pycairo Context to draw to
a (number, number) (x, y) tuple, giving the position of corner a of the triangle.
b (number, number) (x, y) tuple, giving the position of corner b of the triangle.
c (number, number) (x, y) tuple, giving the position of corner c of the triangle.

Example

Here is some example code that draws triangles using the class and the utility function. The full code can be found on github.

from generativepy.drawing import make_image, setup
from generativepy.color import Color
from generativepy.geometry import triangle, Triangle

'''
Create triangles using the geometry module.
'''

def draw(ctx, width, height, frame_no, frame_count):
    setup(ctx, width, height, width=500, background=Color(0.8))

    # The triangle function is a convenience function that adds a triangle as a new path.
    # You can fill or stroke it as you wish.
    triangle(ctx, (100, 100), (150, 50), (200, 150))
    ctx.set_source_rgba(*Color(1, 0, 0))
    ctx.fill()

    Triangle(ctx).of_corners((300, 100), (300, 150), (400, 200)).stroke(Color('orange'), 10)

make_image("/tmp/geometry-triangle.png", draw, 500, 500)
If you found this article useful, you might be interested in the book Computer Graphics in Python or other books by the same author.

Prev
Next

Popular tags

2d arrays abstract data type alignment and animation arc array arrays bezier curve built-in function callable object circle classes close closure cmyk colour comparison operator comprehension context context manager conversion creational pattern data types design pattern device space dictionary drawing duck typing efficiency else encryption enumerate fill filter font font style for loop function function composition function plot functools game development generativepy tutorial generator geometry gif gradient greyscale higher order function hsl html image image processing imagesurface immutable object index inner function input installing iter iterable iterator itertools l system lambda function len line linspace list list comprehension logical operator lru_cache magic method mandelbrot mandelbrot set map monad mutability named parameter numeric python numpy object open operator optional parameter or partial application path polygon positional parameter print pure function pycairo radial gradient range recipes rectangle recursion reduce rgb rotation scaling sector segment sequence singleton slice slicing sound spirograph sprite square str stream string stroke subpath symmetric encryption template text text metrics tinkerbell fractal transform translation transparency tuple turtle unpacking user space vectorisation webserver website while loop zip