Asg 6: Texture mapping

Objectives

• read in an image, e.g., the mandrill.png
• texture map the image onto a simple 2D quadrilateral

Assignment

1. We will not need either of the aw.py or camera.py modules.
2. You can remove these lines frokm gldraw.py

   from camera import Camera
   from aw import AW
   	

   and replace them with

   from PIL import Image
   	

3. You can remove all of the following globals

   global rotating
   global x_angle, x_delta
   global y_angle, y_delta
   global prev_x, prev_y
   global camera
   global aw
   	

   and replace them with

   global texName
   	

   Initialize texName = None in the main() function (remember it is a global).
4. In the init() function
   1. use the global texName and set it via

        texName = glGenTextures(1)
      	

   2. Read in an image using PIL

        # read in texture
        img = Image.open("mandrill.png").rotate(180).transpose(Image.FLIP_LEFT_RIGHT)
        (imw, imh) = img.size
      	

   3. Map the texture to OpenGL's texture memory

        # map texture
        glBindTexture(GL_TEXTURE_2D,texName)
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP)
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP)
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST)
        glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST)
        # target, level, internalFormat, img.w, img.h, border, format, type, texels
        glTexImage2D(GL_TEXTURE_2D,
                     0,
                     GL_RGBA,
                     imw,imh,
                     0,
                     GL_RGBA,
                     GL_UNSIGNED_BYTE,
                     img.convert("RGBA").tobytes())
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE)
      	

   4. Turn on texturing

        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
        glEnable(GL_BLEND)
      
        glEnable(GL_TEXTURE_2D)
      	

5. In the display() function
   1. change

        gluPerspective(65.0, 1.0, 1.0, 1000.0)
      	

      to

        w = glutGet(GLUT_WINDOW_WIDTH)
        h = glutGet(GLUT_WINDOW_HEIGHT)
        gluOrtho2D(0.0,w,0.0,h)
      	

   2. draw a simple quad with normalized texture coordinates

        # render
        glBegin(GL_QUADS)
        glTexCoord2f(0,0)
        glVertex2i(0,0)
      
        glTexCoord2f(1,0)
        glVertex2i(w,0)
      
        glTexCoord2f(1,1)
        glVertex2i(w,h)
      
        glTexCoord2f(0,1)
        glVertex2i(0,h)
        glEnd()
      	

Details

1. There is no computation to be done in this assignment per se, texture mapping mainly requires reading in an image, extracting the image pixels, and transferring them to texture memory.
2. As there is no camera or 3D object to manipulate, you can strip the program of most of that functionality, e.g., no need to initialize any of the variables pertaining to object rotation, no need to initialize objects aw, camera. Those should all be removed.

Requirements

1. Your code should be able to display the mandrill.png image.

Turn in

1. A README file containing
   1. Course id--section no
   2. Name
   3. Brief solution description (e.g., program design, description of algorithm, etc., however appropriate).
   4. Lessons learned, identified interesting features of your program
   5. Any special usage instructions
2. source code (.py source)

How to hand in

Grading scheme