Render Part A Assignment

Diagram

OpenGL

glBegin

glVertex2f

glEnd

glColor3f

glEnable

glPushMatrix

glTranslatef

glRotatef

glPopMatrix

glMap1f

glRasterPos2f

glPixelZoom

glDrawPixels

glClearColor

GLUT

glutBitmapCharacter

Code to Investigate

Cavalcade of Graphics

file to run:

src/main/ruby/cavalcade_of_graphics/cavalcade_of_graphics.rb

Code to Implement

Each of the renderable components has its own file in the src/main/ruby/drawings directory.

Be sure to add accessors for all constructor parameters.

How to use attr_accessor

Equilateral Triangle

file:	src/main/ruby/drawings/equilateral_triangle.rb
class:	EquilateralTriangle
superclass:	Object
methods:	initialize(half_side_length) half_side_length() half_side_length=() render()

wikipedia

WARNING: Ruby division of two integers results in an integer. For example: 1/3 == 0

The triangle should be equilateral, rendered with its the origin at the center of mass.

Your constructor should accept a half_side_length parameter.

Add an accessor for half_side_length.

The height of the triangle should be side_length * sqrt(3)/2

The center of mass is one third from the bottom.

So, the bottom left point A's x coordinate should be -half_side_length and its y coordinate should be -1/3 height.

file to run:

src/main/ruby/drawings/equilateral_triangle.rb

Rectangle

file:	src/main/ruby/drawings/rectangle.rb
class:	Rectangle
superclass:	Object
methods:	initialize(half_width, half_height) half_width() half_width=() half_height() half_height=() render()

Add an accessors for half_width and half_height.

file to run:

src/main/ruby/drawings/rectangle.rb

Ellipse

file:	src/main/ruby/drawings/ellipse.rb
class:	Ellipse
superclass:	Object
methods:	initialize(x_radius, y_radius) x_radius() x_radius=() y_radius() y_radius=() render()

Add an accessors for x_radius and y_radius.

Note: to produce the reference image the code below was used:

    slice_count = 32
    delta_theta = (2*Math::PI) /slice_count

file to run:

src/main/ruby/drawings/ellipse.rb

CircularSegment

file:	src/main/ruby/drawings/circular_segment.rb
class:	CircularSegment
superclass:	Object
methods:	initialize(x_radius, y_radius, theta_a, theta_z) render()

In geometry a chord is a line segment which joins two points on a curve. We will define a class CircularSegment which renders a filled shape of an ellipse cut at the chord between theta_a and theta_z.

Note: to produce the reference image the code below was used:

    slice_count = 32
    delta_theta = (@theta_z-@theta_a) / slice_count

Note: a Chord with 32 slices will have 33 points.

file to run:

src/main/ruby/drawings/circular_segment.rb

Image

file:	src/main/ruby/drawings/image.rb
class:	Image
superclass:	Object
methods:	initialize(path) render()

should draw the pixels from (0,0)

file to run:

src/main/ruby/drawings/image.rb

Text

file:	src/main/ruby/drawings/image.rb
class:	Text
superclass:	Object
methods:	initialize(text, font) render()

file to run:

src/main/ruby/drawings/text.rb

Point2

To support Bézier curves you will want to implement Point2 in point2.rb. You may wish to use Ruby's convenient Struct construct.

You should be able to construct a Point2 with an x and a y and be able to access those values.

Bézier Curve

file:	src/main/ruby/drawings/bezier_curve.rb
class:	BezierCurve
superclass:	Object
methods:	initialize(control_points) render()

NOTE: you need not implement the interpolation yourself. Check cavalcade_of_graphics for an example of how to draw a curve.

Quadratic (Second Order) Curve:
Quadratic (Third Order) Curve:
Fourth Order Curve:

file to run:

src/main/ruby/drawings/bezier_curve.rb

Testing Your Solution

Unit Test

file:

src/test/ruby/drawings/preliminary/part_a/*.rb

UnitTest

note: ensure that you have removed all printing to receive credit for any assignment.

file:

src/test/ruby/drawings/more_comprehensive/part_a/*.rb

UnitTest

note: ensure that you have removed all printing to receive credit for any assignment.

Visual Comparison

file to run:

src/main/ruby/drawings_snapshots/part_a_snapshots_web_page_generator.rb