audio programming - beginner level

Envelope.hpp

#ifndef ADSR_H
#define ADSR_H

#include <vector>
#include <cmath>

namespace ADSR
{
	class Envelope
	{
	public:
		Envelope(float sampleRate,uint32_t duration)
		{
			sampleLength=sampleRate*duration;
			A_l=0.2;A_r=0.9;D_l=0.1;D_r=0.7;S_l=0.4;S_r=D_r;R_l=0.3;R_r=0.0;
		}
		~Envelope() {}
		void generateenvelope(std::vector<float>& env)
		{
			env.resize(sampleLength);
			uint32_t height=600;
			coords[0]=0;// x1
			coords[1]=height;// y1
			coords[2]=sampleLength*A_l;// x2
			coords[3]=height-(height*A_r);// y2
			coords[4]=sampleLength*(A_l+D_l);// x3
			coords[5]=height-(height*D_r);// y3
			coords[6]=sampleLength*(A_l+D_l+S_l);// x4
			coords[7]=height-(height*S_r);// y4
			coords[8]=sampleLength;// x5
			coords[9]=height;// y5
			bridge(env,coords[0],coords[1],coords[2],coords[3]);
			bridge(env,coords[2],coords[3],coords[4],coords[5]);
			bridge(env,coords[4],coords[5],coords[6],coords[7]);
			bridge(env,coords[6],coords[7],coords[8],coords[9]);
		}
		void generateenvelope2(std::vector<float>& env)
		{
			env.resize(sampleLength);
			uint32_t height=600;
			coords[0]=0;// x1
			coords[1]=height;// y1
			coords[2]=sampleLength;// x5
			coords[3]=0;// y5
			bridge(env,coords[0],coords[1],coords[2],coords[3]);
		}
		void generateenvelope3(std::vector<float>& env)
		{
			env.resize(sampleLength);
			uint32_t height=600;
			coords[0]=0;// x1
			coords[1]=0;// y1
			coords[2]=sampleLength;// x5
			coords[3]=height;// y5
			bridge(env,coords[0],coords[1],coords[2],coords[3]);
		}
		void applyenvelope(std::vector<float>& v,std::vector<float>& env)
		{
			for (uint32_t i=0;i<env.size();++i)
			{
				v[i]=v[i]*env[i];
			}
		}
	private:
		void setpt(std::vector<float>& env, uint32_t x, uint32_t y)
		{	
			if (((x >= 0) && (x < sampleLength)) && ((y >= 0) && (y < 600)))
			{
				env[x]=((600.0-float(y))/600.0);
			}
		}
		
		void bridge(std::vector<float>& env, uint32_t x1, uint32_t y1, uint32_t x2, uint32_t y2)
		{
			int x, y, dx, dy, dx1, dy1, px, py, xe, ye, i;
			dx = x2 - x1; dy = y2 - y1;
			if (dx == 0)
			{
				if (y2 < y1) std::swap(y1, y2);
				for (y = y1; y <= y2; y++)
					setpt(env, x1, y);
				return;
			}
			if (dy == 0)
			{
				if (x2 < x1) std::swap(x1, x2);
				for (x = x1; x <= x2; x++)
					setpt(env, x, y1);
				return;
			}
			dx1 = std::abs(dx); dy1 = std::abs(dy);
			px = 2 * dy1 - dx1;	py = 2 * dx1 - dy1;
			if (dy1 <= dx1)
			{
				if (dx >= 0)
				{
					x = x1; y = y1; xe = x2;
				}
				else
				{
					x = x2; y = y2; xe = x1;
				}
				setpt(env, x, y);
				for (i = 0; x<xe; i++)
				{
					x = x + 1;
					if (px<0)
						px = px + 2 * dy1;
					else
					{
						if ((dx<0 && dy<0) || (dx>0 && dy>0)) y = y + 1; else y = y - 1;
						px = px + 2 * (dy1 - dx1);
					}
					setpt(env, x, y);
				}
			}
			else
			{
				if (dy >= 0)
				{
					x = x1; y = y1; ye = y2;
				}
				else
				{
					x = x2; y = y2; ye = y1;
				}
				setpt(env, x, y);
				for (i = 0; y<ye; i++)
				{
					y = y + 1;
					if (py <= 0)
						py = py + 2 * dx1;
					else
					{
						if ((dx<0 && dy<0) || (dx>0 && dy>0)) x = x + 1; else x = x - 1;
						py = py + 2 * (dx1 - dy1);
					}
					setpt(env, x, y);
				}
			}
		}

		float A_l;
		float A_r;
		float D_l;
		float D_r;
		float S_l;
		float S_r;
		float R_l;
		float R_r;
	protected:
		uint32_t sampleLength;
		uint32_t coords[10];
	};
}
#endif