CSE4020 - Computer Graphics -  Lab Assignment 4  - Solved

1. Write down a Python program to draw a transformed triangle in a 2D space.

A.     Set the window title to your student ID and the window size to (480,480).

B.     Complete the render() function below to draw a triangle in the manner described in C.

i. You have to use OpenGL transformation functions. Do not use numpy matrix multiplication for composing transformations. 

def render():
 
    glClear(GL_COLOR_BUFFER_BIT)
    glLoadIdentity()
 
 
 
 
     # draw cooridnates     glBegin(GL_LINES)     glColor3ub(255, 0, 0)     glVertex2fv(np.array([0.,0.]))     glVertex2fv(np.array([1.,0.]))     glColor3ub(0, 255, 0)     glVertex2fv(np.array([0.,0.]))     glVertex2fv(np.array([0.,1.]))     glEnd() 

 

    glColor3ub(255, 255, 255) 

 

    ###########################
    # implement here
 
    ###########################
    drawTriangle() 

 

def drawTriangle():
 
    glBegin(GL_TRIANGLES)
 
    glVertex2fv(np.array([0.,.5]))     glVertex2fv(np.array([0.,0.]))     glVertex2fv(np.array([.5,0.]))
    glEnd()
 
 
 
 
 
 
C.     If you press or repeat a key, the triangle should be transformed as shown in the Table:

Key Transformation 

                              Q      Translate by -0.1 in  x direction

                              E      Translate by 0.1 in x direction

                               A      Rotate by 10 degrees counterclockwise

                              D      Rotate by 10 degrees clockwise

                              1      Reset the triangle with identity matrix

D.     7UDQVIRUPDWLRQVVKRXOGEHDFFXPXODWHGFRPSRVHGZLWKSUHYLRXVRQHXQOHVV\RXSUHVVěĜ

                i.      You may need a global variable (like a python list object) to store key inputs.  

E.      Files to submit: A Python source file (Name the file whatever you want (in English). Extension should be .py) F. Expected result:  

 

 

2. Write down a Python program to draw rotating point p1=(0.5, 0), p2=(0, 0.5) and vector v1=(0.5, 0), v2=(0, 0.5) in a 2D space.

A.     Set the window title to your student ID and the window size to (480,480).

B.     Use the following render() and fill "# your implementation" parts to render p1,p2 and v1,v2.

i.          Hint: Render the vector v1, v2 as a line segment starting from the origin (0,0).

ii.         Hint2: You need different translation matrix for p1 and p2 to render them correctly.

 

def render(th):
 
 
    glClear(GL_COLOR_BUFFER_BIT)
 
    glLoadIdentity()
 
 
    # draw cooridnate     glBegin(GL_LINES)
 

 
 
    glColor3ub(255, 0, 0)
 
 
    glVertex2fv(np.array([0.,0.]))     glVertex2fv(np.array([1.,0.]))
 
    glColor3ub(0, 255, 0)
 
 
    glVertex2fv(np.array([0.,0.]))     glVertex2fv(np.array([0.,1.]))
 
    glEnd()
 
 
    
 
 
 
glColor3ub(255, 255, 255)
 
 
    # calculate matrix M1, M2 using th  
 
# your implementation
 

 
    
 
    # draw point p
 
    glBegin(GL_POINTS)
 
    # your implementation
    glEnd()
 
    # draw vector v
 
 
    glBegin(GL_LINES)
 
 
 
# your implementation
 
    glEnd()
 
 
 C.     Expected result: Uploaded LabAssignment4-2.mp4

                i.       Do not mind the initial angle.

D.       p1,p2 and v1,v2 should be -t rad rotated when t seconds have elapsed since the program was executed.

E.        You need to somehow combine a rotation matrix and a translation matrix to produce the expected result.

                                                                                                                                    '