AdvancedSoftwareRenderer3D/include/buffer.h

#ifndef BUFFER_H
#define BUFFER_H
// ===============================
// AUTHOR       : Angel Ortiz (angelo12 AT vt DOT edu)
// CREATE DATE  : 2018-07-10
// PURPOSE      : Buffer template used as render targets for the software renderer
// ===============================

#include "SDL.h"
#include <type_traits>
#include <string.h>

//Templated struct to emulate GPU buffers such as 
//the frame buffer and the ZBuffer 
//Also keeps track of a bunch of useful data about itself
template<class T>
struct Buffer{
        int mWidth, mHeight, mPixelCount, mPitch, mOrigin;
        T *buffer;

        //The buffer is actually just a simple 1D array which we access using an equation
        //Notice how it's not the usual (y*width + x) equation that you see for most quasi 2D arrays
        //This is because the origin is at the lower left (instead of upper left) and y moves upwards
        T& operator()(size_t x, size_t y){
            return buffer[mOrigin + -y*mWidth + x];
        }

        Buffer(int w, int h, T * array) 
        : mWidth(w), mHeight(h), mPixelCount(w*h), mPitch(w*sizeof(T)),
          mOrigin(mHeight*mWidth - mWidth), buffer(array){}

        ~Buffer(){delete [] buffer;}
        
        //Cannot use memset to clear a float since the binary
        //Representation is more complex. We just iterate through the whole
        //thing and explicitely set it to zero instead
        void clear(){
            if(std::is_same<T,float>::value){
				for(int i = 0; i < mPixelCount;++i){
					buffer[i]  = 0.0f;
				}
            }
			else{
				//Set to a 15% white color to make it nicer looking.
				memset(buffer,0xD, mPitch*mHeight);       
			}
        }
};

#endif