PRESENTATION ON -:

Q CAD

BY-:

VIKAS MAHAJAN

(D1 IT2)

7675

ABOUT COMPANY

QCad is developed by RibbonSoft. Development on QCad began in October 1999, starting with code from CAM Expert. QCad 2, designed to "make QCad more productive, more user friendly, more flexible and increase its compatibility with other products" began development in May 2002.

Much of the interface and concepts behind use are the same of those of AutoCAD.

QCad uses the AutoCAD DXF file format internally and to save and import files.

ABOUT SOFTWARE

QCad is an application for computer aided drafting in two dimensions (2d). With QCad you can create technical drawings such as plans for buildings, interiors, mechanical parts or schemas and diagrams. QCad works on Windows, Mac OS X and many Linux and Unix Systems. The source code of the QCad community edition is released under the GPL (Open Source). Precompiled packages are available for some Linux platforms, such as Debian, via the distribution's package manager.

History of QCad

The Beginning

The project QCad started in October 1999 as a fragment of CAM Expert, which is a CAM System for engraving and LASER cutting. CAM Expert was capable of enough CAD functionality that a spinoff for an independent CAD system made sense.

QCad 1

QCad 1 was an overwhelming success. Within about two years it had an estimated user base of about 70'000, probably more. Its user interface was available in 20 languages and it received top ratings and awards on several occasions.

QCad 2

QCad 2 was first released in September 2003. It has been designed with modularity and future extensions in mind. Moreover a couple of interesting libraries and side products evolved out of the QCad 2 development process: the QCad libraries, dxflib and vec2web.

Main Features

Layers

Blocks (grouping)

35 CAD fonts included

Metrical and Imperial units

DXF input / output

Printing to scale

Over 40 construction tools

Over 20 modification tools

Construction and modification of points, lines, arcs, circles, ellipses, splines, polylines, texts, dimensions, hatches, fills, raster images

Various powerful entity selection tools

Object snaps

Measuring tools

Part library with over 4800 CAD parts

Scripting interface

Basic CAD Concepts

1. Entities

Entities are graphical objects in a CAD system. Typical entities which are supported by most CAD systems are: points, lines and circular and elliptical arcs. More complex and CAD specific entities include polylines, texts, dimensions, hatches and splines.

2. Attributes

Every entity has certain attributes such as its color, line type and line width.

3. Layers

A basic concept of computer aided drafting is the use of layers to organize and structure a drawing. Every entity of a drawing is on exactly one layer and each layer can contain any number of entities. Typically, all entities with a common 'function' or with common attributes are constructed on the same layer. Every layer has attributes (color, line width, line style) and the entities on a layer usually inherit their attributes from the layer they are placed on.

Figure 1 shows an example drawing that uses layers. All dimensions of the drawing are placed on a layer named 'dimensions'. The color of all 'dimension' entities isdefined by the layer and can be easily changed by changing the color of the layer 'dimensions'.

4. Blocks

A block is a named group of entities. Blocks can be inserted into the same drawing more than once at different locations, with different attributes, scaling factors and rotation angles (see Figure 2). Such instances of a block are usually called 'inserts'. Inserts have attributes just like other entities. An entity that is part of an insert can have its own attributes, inherit its attributes from the layer it is placed on, or inherit them from the insert it is part of. Once created, inserts are still dependent on the block they instantiate. The power of inserts is, that you can modify a block and all inserts that were previously made from that block will be updated to reflect the changes.

5. Drafting in CAD

In many ways, CAD is similar to traditional drafting. When drawing a plan or a view of an object on a paper, you would use tools such as a ruler to draw lines. CAD systems offer many tools to achieve the same goal. The big advantage of a CAD system is the fact that you can change every entity of your drawing easily after you have created it. When working with a CAD system you will very often create lines that will not be on the final printout or which don't have the correct length and need to be trimmed later (see Figure 3). A common mistake of CAD beginners is wanting to create the final drawing right away. Never hesitate to create an auxiliary construction if it helps you to define or verify a part of your drawing.

6. Coordinate Systems

A good understanding of how the most common coordinate systems work is absolutely essential if you are to make the best use of any CAD program. If you are not familiar with coordinates it is highly recommended that you take some time to familiarize yourself with this fundamental concept.

Origin

The origin (or origin point) of the drawing is the point where the X and Y axis cross each other. It is also the absolute zero point of the drawing.

Relative Zero Point

In addition to the absolute zero point, there is also a relative zero point in QCad. The relative zero point can be moved to any location by the user as a temporary reference for a local construction.

Cartesian Coordinates

The Cartesian coordinate system is the standard coordinate system that is usually used if no other system is specified. In the Cartesian coordinate system, the position of a point can be described by its distance from two axes, X and Y. Cartesian coordinates are usually written in the format:

x-ordinate,y-ordinate

For example the coordinate 3.5,7 is located 3.5

units to the right and 7 unit to the top of the origin.

Cartesian coordinates can also originate in a position

different from the origin. In that case we talk about

'relative coordinates' There is no standard

notation for relative Cartesiancoordinates, but in

QCad they are written in the format:

@x-ordinate,y-ordinate

Polar Coordinates

Polar coordinates use a distance and an angle

to describe the position of a point. The angle 0

is alwayspointing to the right on your screen

(east). In QCad, polar coordinates are noted

in the format:distance