1D convection

testApp.cpp

#include "testApp.h"

void testApp::setup(){
	ofSetFrameRate(60);
	ofBackground(22,33,44);
	
	gif.setup(ofGetWidth(), ofGetHeight());
	record = false;
	
	// setup some initial data.
	dt = 0.1;
	for(int i = 0; i < N; ++i) {
		u[i] = ofNoise(dt * i);
	}
}

void testApp::update(){
	stepConvection(u);
}

void testApp::draw(){
	drawConvection(u);
	
	if(record && ofGetFrameNum() % 5 == 0) {
		ofImage img;
		img.grabScreen(0,0,ofGetWidth(), ofGetHeight());
		gif.addFrame(img.getPixels());
	}
}


void testApp::drawConvection(float* data) {
	float s = ofGetWidth()/N;
	float y = ofGetHeight() * 0.5;
	y = 0;
	float h = 100.0f;
	
	// draw lines
	glColor3f(1,1,1);
	glBegin(GL_LINE_STRIP);
	for(int i = 0; i < N; ++i) {
		glVertex2f(i*s, y+data[i]*h);
	}
	glEnd();


	// draw dots.
	glColor3f(0,0.4,0.6);
	glPointSize(5);
	glBegin(GL_POINTS);
	for(int i = 0; i < N; ++i) {
		glVertex2f(i*s, y+data[i]*h);
	}
	glEnd();
}


void testApp::stepConvection(float* data) {
	int dx = float(mouseX)/ofGetWidth() * N;
	dx = std::min<int>(std::max<int>(0, dx), N-1);
	data[0] = ofNoise(ofGetElapsedTimeMillis()*0.001)*2;
	
	memcpy(u_copy, data, sizeof(float) * N);
	for(int i = 1; i < N; ++i) {
		data[i] = u_copy[i] - u_copy[i] * dt * (u_copy[i] - u_copy[i-1]);
	}
}



void testApp::keyPressed(int key){	
	if(key == 'r') {
		record = !record;
	}
	else if(key == 's') {
		gif.save("wave_convection.gif");
		record = false;
	}
}


void testApp::keyReleased(int key){}
void testApp::mouseMoved(int x, int y){}
void testApp::mouseDragged(int x, int y, int button){ }
void testApp::mousePressed(int x, int y, int button){ }
void testApp::mouseReleased(int x, int y, int button){ }
void testApp::windowResized(int w, int h){ }
void testApp::gotMessage(ofMessage msg){ }
void testApp::dragEvent(ofDragInfo dragInfo){ }

testApp.h

#pragma once

#include "ofMain.h"
#include "Gif.h"

#define N 32

using namespace roxlu;

class testApp : public ofBaseApp{
	public:
		void setup();
		void update();
		void draw();
		
		void keyPressed(int key);
		void keyReleased(int key);
		void mouseMoved(int x, int y);
		void mouseDragged(int x, int y, int button);
		void mousePressed(int x, int y, int button);
		void mouseReleased(int x, int y, int button);
		void windowResized(int w, int h);
		void dragEvent(ofDragInfo dragInfo);
		void gotMessage(ofMessage msg);

		float dt;
		float u[N];
		float u_copy[N];
		void drawConvection(float* data);
		void stepConvection(float* data);
		Gif gif;
		bool record;

};