/*
// Chunk 54 - Sine in Action
// Plots a sine function by colouring surrounding pixels
// in relation to their proximity to the sine wave
*/
float theta0 ; //Start angle
float dTheta0; // Increment start angle 'angular velocity'
float dTheta; // Value for incrementing theta, a function of period
float amplitude; // maximum height of wave
float amplitude0; //intial undamped amplitude
float damping; //decrase in height over period of wave
float frequency; //repetitions of wave within 2Pi radians
int count = 1;//use to reverse gradient
int range; //range for vertical movement of function
int colorChoice; //colour type to plot
int adjustmentChoice; // choice of funtion to adjust postion of sine wave
PImage img;
void setup() {
size(500, 500);
frameRate(20);
img = createImage(250,250,RGB);
noSmooth();
setOptions();
}
void draw() {
background(255);
amplitude = amplitude0;
theta0 += dTheta0; //increment initial angle
if ( frameCount % range == 0){
count = -count;
}
//set colours of image
float theta = theta0; //set initial angle for calculating sin wave
int intColor; // value of colour to plot at x,y
color c; //colour of plotted point x,y based on intColor
float adjSinWave; // y value to plot colour around
//plot sin function by colouring surrounding points
for (int x = 0; x < img.width; x++) {
adjSinWave = adjustment(x, adjustmentChoice) + plotSinWave(theta);
for ( int y= 0; y < img.height; y++){
intColor = getColorValue(adjSinWave, y);
c= getColor(intColor,colorChoice);
img.set(x,y,c);
}
theta += dTheta;
}
// display the results
image(img,0,0,width,height);
}
void setOptions(){
float period = 450.0; // How many pixels before the wave repeats
//values for plotting sine wave
theta0 = 0;
dTheta0 = 0.01;
dTheta = TWO_PI / period; //change in angle plotted between x and x+1
amplitude0 = img.height/2; //amplitude looks best close to height/2
damping = 0.987; //keep close to 1, or sine function becomes quickly flat
frequency = 6;
range = img.height;
colorChoice = 2; // 1- grayscale, 2 - colour shift,
adjustmentChoice = 3; //1 - constant, 2 - linear, 3 - sin & linear
}
float plotSinWave(float angle){ //main sine wave to plot everything else round
// float result = 0; //for testing colour distibution
float result = amplitude * sin (frequency * angle);
amplitude = amplitude * damping;
return result;
}
float adjustment(float xPos, int choice){ //adjustment to position of sine wave
float result = 0;
if (choice == 1){ //constant
result = img.height/2;
}
else if (choice ==2) { //simple linear function
int intersect = 0;
float gradient ;
float gradientChange =0;
if (count > 0 ){ //count switches from positive to negative when framecount % range is reached
//increase intersect up to range
gradientChange = frameCount % (range);
}
else {//decrease intersect from range to zero
gradientChange = range - frameCount % (range);
}
gradient = (img.height - gradientChange) / img.width;
result = intersect + gradient * xPos ;
}
else if (choice == 3){//combination of sin and linear functions
float amp1 = 0.25;
int freq1 = 1;
int period1 = img.width;
float amp2 = 5;
int freq2= 2;
int period2 = img.width/3;
int intersect = 0;
float gradient;
gradient = amp1 * sin(freq1 * (xPos * TWO_PI/period1));
if (count > 0 ){ //count switches from positive to negative when framecount % range is reached
//increase intersect up to range
intersect = frameCount % (range);
}
else {//decrease intersect from range to zero
intersect = range - frameCount % (range);
}
//linear function with variable intersect and gradient
float result1 = intersect + gradient * xPos;
float result2 = amp2 * sin(freq2 * (xPos * TWO_PI/period2));
result = result1 + result2;
}
return result;
}
int getColorValue(float maxValue, float value){
//colors plotted around sine wave
// returns int value between 0 & 255 based on distance from maxValue
float h = img.height;
float temp = 0;
int result;
float minValue;
float rangeColor;
// if maxValue > h/2 then minValue is 0 else minValue 2 * maxValue - h
minValue = min(0, 2* maxValue - h);
//color increasing to maxValue
if ( value <= maxValue){
temp = value - minValue ;
}
else { //color decreasing from maxValue
temp = 2 * maxValue - (value + minValue );
}
rangeColor = max(maxValue, h - maxValue); //range over which colour varies between 0 and 255
temp = scaleValue(temp, 0, rangeColor); //scale value to be between 0 and 255
result = round(temp); //convert scaled value to int
return result;
}
float scaleValue(float z, float minVal, float maxVal){
//adjust values to ensure minimum equals 0
float adjZ = z - minVal;
//Scale values to ensure new max equals 255
float adjMaxZ = maxVal - minVal;
float scaledZ = adjZ * (255/adjMaxZ);
return scaledZ;
}
color getColor(int colorVal, int choice){
int tempColor;
int redVal = 0;
int greenVal =0;
int blueVal =0;
if (choice == 1){ //grayscale
redVal = greenVal = blueVal = colorVal;
}
else if (choice == 2 ){// Smooth transition of color from blue to green to yellow to red
//subdivide colour selection based on range of values
if ( colorVal >= 0 && colorVal <= 63){
tempColor = 4 * colorVal;
redVal = 0;
greenVal = tempColor;
blueVal = 255;
}
else if ( colorVal > 63 && colorVal <= 127){
tempColor = 4 * (colorVal - 64);
redVal = 0;
greenVal = 255;
blueVal = 255 - tempColor;
}
else if ( colorVal > 127 && colorVal <= 191){
tempColor = 4 * (colorVal - 128);
redVal = tempColor;
greenVal = 255;
blueVal = 0;
}
else if ( colorVal > 191 && colorVal <= 255){
tempColor = 4 * (colorVal - 192);
redVal = 255;
greenVal = 255 - tempColor;
blueVal = 0;
}
}
return color(redVal,greenVal,blueVal);
} |
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