Spectrum.h

Spectrum.h

#pragma once

#include "ofMain.h"

class Spectrum
{
public:
  
	Spectrum() : buffer_size(100), x_scale(0.001) {}
	
	void setBufferSize(int n)
	{
		buffer_size = n;
	}
	
	inline void update(const vector<float>& line)
	{
		update(&line[0], line.size());
	}
	
	void update(const float *ptr, size_t len)
	{
		buffer.push_front(vector<float>());
		vector<float>& amp = buffer[0];
		amp.resize(len);

		for (int i = 0; i < len; i++)
		{
			float d = ofMap(i, 0, len, 0, 1);
			d = d * d;
			
			int index = d * (len - 1);
			float sample = ptr[index] * (expf(i * x_scale) - 1);
			max_sample = max(max_sample, fabs(sample));
			amp[i] = sample;
		}

		if (buffer.size() > buffer_size)
		{
			buffer.pop_back();
		}
		
		// update mesh
		ofMesh mesh;
		
		for (int y = 0; y < buffer.size(); y++)
		{
			float yy = ofMap(y, 0, buffer.size(), 0, 1);
			vector<float> &smp = buffer[y];
			
			for (int x = 0; x < smp.size(); x++)
			{
				float xx = ofMap(x, 0, smp.size(), 0, 1);
				mesh.addVertex(ofVec3f(xx, yy, smp[x] / max_sample));
			}
		}

		for (int y = 0; y < buffer.size() - 1; y++)
		{
			for (int x = 0; x < len - 1; x++)
			{
				int index = y * len + x;
				
				int idx0 = index;
				int idx1 = index + 1;
				int idx2 = index + len;
				int idx3 = index + len + 1;
				
				mesh.addTriangle(idx0, idx1, idx2);
				mesh.addTriangle(idx1, idx3, idx2);
			}
		}
		
		this->mesh = mesh;
	}
	
	void draw(float width = 100, float height = 100, float amp = 100)
	{
		glPushMatrix();
		glScalef(width, height, amp);
		for (int y = 0; y < buffer.size(); y++)
		{
			float yy = ofMap(y, 0, buffer.size(), 0, 1);
			vector<float> &smp = buffer[y];
			
			glBegin(GL_LINE_STRIP);
			for (int x = 0; x < smp.size(); x++)
			{
				float xx = ofMap(x, 0, smp.size(), 0, 1);
				glVertex3f(xx, yy, smp[x] / max_sample);
			}
			glEnd();
		}
		glPopMatrix();
	}
	
	ofMesh getMesh() { return mesh; }
	
	void resetPeak()
	{
		max_sample = 0;
	}
	
protected:
	
	int buffer_size;
	float max_sample;
	
	float x_scale;
	
	deque< vector<float> > buffer;
	ofMesh mesh;
};