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Topic: multidimensional arrays (Read 456 times) |
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jbk303
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multidimensional arrays
« on: Apr 2nd, 2003, 1:15pm » |
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I am writing a program that will apply the Karplus-Strong plucked string algorithm to an array of colors. I decided to implement this using a 100 by 3 array. The compiler throws a NullPointerException. I have tried just about everything I can think of except 3 one dimensional arrays, which would be slower.
Does anyone have any ideas?
<CODE>
float[][] carray= new float[100][3];
int b=2;
int c=1;
color k = color(0,0,0);
int qw=0;
void setup() {
carray = new float[100][3];
size(100,200);
for(int i=0; i<100; i++) {
for(int ii=0; i<3; i++){
carray[i][ii]=random(0,255);
}
}
}
void loop() {
qw++;
b+=c;
c=-1*c;
//println(b);
for(int i=0; i<100; i+=b){
for(int ii=0; ii<3; ii++){
carray[i][ii]=(carray[i][ii]+carray[i+1][ii])/2;
carray[i+1][ii]=(carray[i][ii]+carray[i+1][ii])/2;
}
}
for(int i=0; i<100; i++){
k = color(carray[i][1], carray[i][2], carray[i][3]);
point(i, qw);
}
}
</CODE>
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benelek
 
 
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Re: multidimensional arrays
« Reply #1 on: Apr 2nd, 2003, 2:31pm » |
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as far as i can see, u have two problems:
1. ur defining a variable of type "color" before the setup() section. this will work:
Code:void setup() {
size(100,100);
k = color(0,0,0);
}
color k;
void loop() {
} |
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but this will not:
Code:void setup() {
size(100,100);
}
color k = color(0,0,0);
void loop() {
} |
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2. ur getting an outOfBounds exception a few times because ur trying to access carray[bla][3], where only carray[bla][0 to 2] exists. for instance:
Code:
k = color(carray[i][1], carray[i][2], carray[i][3]); |
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and a similar problem with accessing i=99 and i+1=100 in...
Code:
carray[i+1][ii]=(carray[i][ii]+carray[i+1][ii])/2;
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but i've never heard of the Karplus-Strong plucked string algorithm. mind explaining the idea?
-jacob
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jbk303
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Re: multidimensional arrays
« Reply #2 on: Apr 3rd, 2003, 1:48am » |
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Thanks, that cleared up those errors. The karplus-strong algorithm takes a wavetable filled with a noisy sound sample and reads it, averages the current and previous samples, and feeds the average back into the wavetable. This is done until the wavetable contains a uniform value. In other words: it repeatedly lowpasses the sample. I thought it might be cool to visualize. Once I have this working it will need some tweaks to look better. Thanks for your help,
Josh
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