Objectives:  In this lab, you will learn:

1. -OpenGL texture mapping
   

2. -OpenGL picking
   

3. -Rendering transparent objects
   

4. -Output frame buffer content
   

1. (4 pts) Add OpenGL textures to your scene:
    a Choose appropriate images to decorate your scene objects
    c. Use key stroke 'x' to turn on/off the textures

2. (3 pt) Allow OpenGL picking, where the user will use mouse to click on any of the objects in the scene. Whatever object gets picked will be displayed in a unique color of your choice that can be easily distinguished from its surroundings.

3. 3.(2 pts) Create a picture-in-picture effect. Put an additional camera in the scene and render the scene using that camera into a small window at the upper left corner of your display window.  Use key ‘p’ to toggle this effect.
   

4. 4.(2 pts) Render your OBJ model(s) using vertex buffer objects (VBO).
   
   5. (2 pts) Add a semi-transparent object to the scene. To do this you need to use OpenGL's alpha blending feature. In essence, you need to enable OpenGL blending by calling the function glEnable(GL_BLEND), and set up the blending function using glBlendFunc(). The parameter in this function should be GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALHPA. Also, you need to use glColor4f() with the last parameter as the opacity (range: [0-1]; 1: opaque; 0: transparent) This semi-transparent object should be the last object to draw in your display function. Read the description in the red book.
   
   6. (2 pts) Finally, allow the program to output the image to a file by pressing the key stroke 'o'. To do this, you need to read the frame buffer back to memory by using the function glReadPixels(). For instance, calling glReadPixels(0, 0, ScreenWidth, ScreenHeight, GL_RGB, GL_UNSIGNED_BYTE, Image) will dump the frame buffer (RGB pixels) to an array named 'Image' in your memory which is declared by you and has dimensions ScreenWidth*ScreenHeight*3 with the type as unsigned character. Output the memory content to a ppm file. Below is a pseudo code of writing out ppm files.
   
                FILE *fp;
                
                fp = fopen("out.ppm","w");
                int height = ScreenHeight; // you need to know this from somewhere else
                int width = ScreenWidth; // same here.
                int max_ccv = 255; // Write the 'header' information
                fprintf(fp,"P3 %d %d %d\n", width, height, max_ccv);
              
                for each row, for each pixel, write out an integer value from 0 to255 for each of the R, G, B color components
   
                fclose(fp);
   

Extra credits:

(1 point)  Map textures to your OBJ models using the principles we discussed in class such as mapping vertices to spherical or cylindrical coordiates.

(1 point) Use OpenGL’s curves and surfaces to create objects (Chapter 12 in the text book)

Submitting Files

What to submit? 

Your program source files

The Visual Studio solution and project files you use to compile your program.

A simple readme file if you have any instructions about how to compile and use your program.

Do not submit any executable or object files.

In order to submit files for cse581  lab4, use the following command:

submit c581aa lab4 < names of all your files>

Important Note about the 'submit' program

The 'submit' program submits all of the files at once,  not  one at a time, previous submissions for a given lab are completely removed.  Or put another way; each time the  submit command is issued for a given lab, ALL of the previously submitted files are clobbered.

That means that

          submit c581aa lab4 lab4.c
          submit c581aa lab4 readme

will result in ONLY 'readme' remaining in the lab1 submission

You should do the following:

          submit c581aa lab4 lab4.c readme
          or
          submit c581aa lab4 lab4_dir

Where 'lab4_dir' is a directory containing all of  the  lab1 files to be submitted, or best of all (for both student and grader) is:

          cd lab4_dir
          submit c581aa lab4

Submit will immediately print submission information to  the submitter. Use 'man submit' if you have any other questions.

Late Penalty

You should submit your lab on time. We are on a quarter schedule, which is pretty tight. Being late for one lab could affect the time left for you to complete subsequent labs. All labs are due at 11:59pm of the specified due data, and there is a 10% penalty each day for up to 50%. After that, you get zero.

Grading Criteria

Grading of the labs will be based on the following:

•90%: Correctness and adherence to assignment specification.

•10%: Readability, structure of code, use of comments, adherence to lab procedures (submitting, naming conventions, etc.)

The grader will grade the labs. If you have problems with the grade you received on your lab, see the grader first. If you can't resolve the dispute with the grader, then see me. However, in order to maintain consistent grading for everyone in the class, I am not very inclined to alter grades that are assigned by the grader.

Don't copy labs. Discussion of lab assignments is allowed and encouraged. However, you need to complete the lab all by yourself. Labs which are too similar will be handed over to the Committee on Academic Misconduct and handled by them.