Screencast DrGeo

From OFSET Community Wiki

Contents 1 Introduction 2 Starting with Dr. Geo II 3 Basic tools 3.1 Point tools 3.2 Curve tools 3.3 Transformation tools 3.4 Numeric tools 3.5 Other tools 4 Advanced tools 4.1 Macro-construction 4.2 Smalltalk programmed figure 4.3 Smalltalk script 5 Misc examples 6 Technical note

Introduction

These videos demonstrate most of the DrGeo features: basic manipulations, simple construction, use of the advanced integrated programming tools.

Note: In some video, halo are used, to show a halo surrounding graphic elements of the user interface, depending on your platform you need to press the right mouse button, or combination of key like Alt+clic. See Squeak, un Smalltalk libre multimédia.

Starting with Dr. Geo II

In the following video, I show basic operations with DrGeo.

• Opening a figure
• Zooming, moving an example figure

Basic tools

Point tools

• Free point, point on curve
• Intersection point
• Middle of two points
• Middle of a segment
• Point define by coordinates

Curve tools

• Line
• Ray
• Segment
• Vector
• Circle defined by two points
• Circle defined by center and radius
• Arc
• Polygon
• Locus

Transformation tools

• Parallel line
• Perpendicular line
• Central symmetry
• Axial symmetry
• Translation
• Rotation with geometric angle in degree
• Rotation with oriented angle in degree
• Scale

Numeric tools

• Distance : distance between two points, a point and a line, segment length, vector norm, arc length, circle perimeter, line slope
• Geometric angle
• Oriented angle
• Free value you can change at will

Other tools

• Undo/redo commands
• Erase
• Style on object: change aspect, edit object name, edit value. Demonstrated for the various item categories
• Gridding

Advanced tools

Macro-construction

• Recording a macro-construction
• Playing a macro-construction

Smalltalk programmed figure

It is a progressive collection of screencasts. You should view all once in the listed order bellow.

• Demonstration of Smalltalk programmed figure
• Write a programmed triangle
• Write a programmed triangle with randomized summit
• Write programmed recursive triangles
• Point defined with a block of code to update its coordinates, here compute the closest point on a polygon to another point.

Smalltalk script

• Write and use a script without any argument
• Write and use a script with one argument
• Write and use a script with two arguments
• Write and use a script returning a Point instance
• A funny example using Smalltalk script and the homothety transformation

Misc examples

Several misc examples of use can be view at ftp://ftp.ofset.org/squeak/drgeo. Beware these screencasts are based on earlier version of DrGeoII and the video quality may not be as good as the previous ones.

Technical note

If you want to collaborate on that page, just write to hilaire@ofset.org, I create an account for you.

The video are encoded with the maximum quality, at a screen resolution not higher to the PAL DVD format (720x576). However it can be at a lower screen resolution.

To produce the screencast, I use recordmydesktop with the maximum video quality at 8 fps and no sound:

recordmydesktop --no-sound --windowid 0x3800002 --fps 8 -o 003-advanced-record-in-menu

With some of these screencasts we produced a video clip presenting Dr. Geo II.