OOD Assignment – To be performed in groups of three people.
Your task is to write a 2D graphics engine for drawing composite objects out of basic primitives. Your program will read in a file containing a description of a scene in terms of n sided polygons and circles along with 2 basic types of manipulation (a 2D translation and a 2D scale). Your program will then turn this description into a 2D line drawing. Below are two examples for you to test your programs with, along with the picture that your program should produce.
Sample 1 file and the resulting picture
Sample 2 file and the resulting picture
A 3rd unseen file will be used in testing to see if your program operates correctly.
You’ll be glad to know that you are not expected to build your graphics application from scratch and a sample application has been assembled to simplify the use of graphics. Please copy it to your local directory and compile it (make -f makefile_shape). The program uses openGl and glut, although these have been hidden away as much as possible so should not concern you. Should you wish to develop upon another platform you will need to install Glut to use the sample code.
All the rendering should occur within the draw function ( see example ), this unfortunately means you may need some global variables but the use of the static keyword will minimise this. Any initialisation within main should be done before the window object is instantiated.
Some basic openGl commands you will need to know are glColor3f(r,g,b); sets the colour to that specified by r,g,b.
glBegin(GL_LINE_LOOP);
glVertex3f( 0.0f, 1.0f, 0.0f); // Top
glVertex3f(-1.0f,-1.0f, 0.0f); // Bottom Left
glVertex3f( 1.0f,-1.0f, 0.0f); // Bottom Right
glEnd();
This draws 3 connected vertices. You can have any number of vertices listed between the glBegin and glEnd commands.
glTranslatef(x,y,z) translates the cursor on the screen as we are only dealing with 2D you can keep z set to 0.0
glScalef(x,y,z) scales the objects being drawn, again as we are only dealing with 2D you can keep z set to 1.0
You shouldn’t need to know anything more about OpenGL and rendering than that but should you wish, more details can be found here .
Design Specification Hints.
Use polymorphism to build an object which renders differently depending upon the type of object. That object may be a polygon, a circle, a translation or a scaling.
Use overloaded input/output operators to read in the content of the file
Assessment
The project will be assessed in three parts:
1) Initial Design: description of design and specification [20%] Due Tues 22/11/11 4pm (16:00).
2) Quality of code; good structure, correct use of language features, clarity of implementation, error checking, good comments [60%] Due Tues 13/12/11 4pm (16:00).
3) Working code: demonstration of full implementation [20%] To be performed in laboratory session 15th December.
Submission details:
Title: Preliminary Design
Due Date: Tues 22/11/11 4pm (16:00). .
Length: 1 Page Max A4 11pt text
Contents: The title, names of members of group and login id’s. Provide an overall software design (with diagram of class hierarchy), comment in general terms about how your design solves the problem, you might also want to comment on the memory management used, error handling and any additional related class and functionality implemented.
Title: Final Submission
Due Date: Due Tues 13/12/11 4pm (16:00) . You will demonstrate your program in the laboratories on the 15th Dec 2011.
Length: 1 Page A4 11pt text + compact printout of code
Content: A Title page stating team members names and login id’s and declaring their contributions to the project i.e. 33% each. Each student should sign this declaration to show they agree with the weight of their contribution. A clear class hierarchy diagram should be included followed by a compact printout of the code.
A hardcopy of assignments whether postgrad or undergrad should be submitted to the appropriate assignment submission box or office prior to the deadline. No electronic submission is required this year unless I decide I need to do a plagiarism test. In which case you will be contacted.
Failure to adhere to these guidelines will result in marks being deducted. There will be no extensions. Work handed in late will suffer the standard penalties laid out by the school.
Working code demonstrations in the labs on the 15th of December must be performed on the faculty linux computers (most likely those in the penguin lab), demonstrations on laptops or windows will not be marked.
Feedback and Marking: The purpose of the initial design is to force the students to think about the problem and solution prior to implementation. Feedback on design will be given to the whole cohort in the lecture immediately following submission (24 th Nov). In this lecture an idealised design will be discussed. This will allow students to judge the suitability of their own designs and make amendments prior to implementation. A mark for the design will be provided at a later date. The final implementation will be marked against the attributes: Design Quality, Code Structure, Use of Language Features, Clarity of Implementation, Error Checking and Comments. Feedback will also be provided on the strengths and weaknesses of the implementation.
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