• class PPMpixmap
  {
   public:
   //methods:
   PPMpixmap();      //constructor, which initializes maxColors to 256, nRows, nCols to 0
   ~PPMpixmap();     //destructor
   bool readPPMfile(string filename);
                                                   //opens filename (returns false if unable to open file), reads and assigns values
                                                  // to inRows, nCols, maxColors, and pixel. Returns true if successful.
   //data:
   int nRows, nCols; //dimension of the image
   int maxColors;    //maximum number of shades each color (r,g,b)
   Color3 *pixel     //dynamic array of pixels
  }

The code for readPPMfile is found in our files directory.
      

• class TextureInfo
  {
   public:
   //methods:
   void setWhich(int which); //index of the image
   void setFrame(GLdouble l, GLdouble r, GLdouble b, GLdouble t); //left, right, bottom, top on generic plane or square
   void setImage(GLint w, GLint h); //dimension of the image
  
   //data:
   int whichone, width, height;
   GLdouble frame_left, frame_right, frame_bottom, frame_top, frame_width, frame_height;
  }
  

• add these data fields to class Primitive :

  bool isTextured; //default is false, set in the constructor
  TextureInfo texture;

Scene Class:

• Add data member:
    PPMpixmap image[15]; //max of 15 image pixel maps in the scene (purely arbitrary; add more if you want)
  
  
• Add to readScene:
  if (identifier == "IMAGES")
  {
    infile>>identifier;
    while(identifier!="ENDIMAGES")
    {
      image[numImages].readPPMfile(identifier);
      numImages++;
      infile>>identifier;
    }
  }
  
  
• Add to readScene, within the WORLDBEGIN and WORLDEND,
  if (identifier == "texture")
  {
    set "isTextured" for this primitive to be true;
      infile>>which;  //local integer variable
    for this primitive, call texture.setWhich(which);
    infile>>left>>right>>bottom>>top; //local (to readScene) GLdouble variables
    for this primitive, call texture.setFrame(left, right, bottom, top);
  }
  
  
• Add code to shader method so that it renders textured surfaces:

  
  After calculating phong,
       Assign diffuse and ambient to be the object's material diffuse and ambient. If the object is not textured, these will not change.
       If the object is textured,
       {
             if the object is a square or a plane
             {
                 set the generic hit point, GH
                 if GH is within the texture frame
                 {
                    set local variable j to be which texture;
                    set local variables for numColors, nCols and nRows //these locals are set merely for convenience;
                    calculate which row (tex_row) and which column (tex_col) of the image map the pixel is in;
                    calculate and assign whichpix to be the correct entry for this pixel (tex_col, tex_row) of the image array, which is one-dimensional;
                    assign local variable diffuse to be the red, green, blue components in this array entry, divided by the number of colors;
                    assign local variable ambient to be the diffuse values * 0.3 (or some other appropriate fraction)
                 }
              }
       }

  Then continue on with lighting calculations as before.

Test Files:

Tese test files for textures are located in /classes/cs3114/RayTracing/files/texture directory, along with the appropriate PPM files:

• tex1.scn
• tex2.scn
• tex3.scn
• tex4.scn
• ts.scn
• wood.ppm
• sunrise.ppm
• dog.ppm
• shingle.ppm