sin() and angle issue of two-dimensional arrays(tutorial)

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burakkaan

sin() and angle issue of two-dimensional arrays(tutorial)

in Programming Questions • 2 years ago

Hello,
i've been studying processing for the last 2 weeks from http://processing.org/learning/
i have never studied any other programing before (except html and css like 7-8 years before), but it has been going well, i have understood up to the logic and method of arrays but i'm trying to understand the example in
http://processing.org/learning/2darray/ but even though i have read reference page of sin() i couldn't understand "Oscillation" step and "sin wave" step.

Could someone please explain the last two steps to me a bit clearer.

thank you!
Burak

Replies(4)

alphachap

Re: sin() and angle issue of two-dimensional arrays(tutorial)

2 years ago

I don't know if I get what you mean, but here is some comments.

void display() {
    stroke(255);
    // Color calculated using sine wave
    fill(127+127*sin(angle));
    rect(x,y,w,h);
}
>>here the color of the rectangle will vary in the range [127-127..127+127] or basically [0..255] as the angle varies

void oscillate() {
angle += 0.02;
}

>>here the oscillate() method varies the angle, which will cause the sin(angle) value to oscillate between -1..1

void draw() {
background(0);
     // Color calculated using sine wave
     grid[i][j].oscillate();
      grid[i][j].display();
    }
}
}
>>here the oscillate is activated. Remember that draw() is a loop, it is executed over and over again.

PhiLho

Re: sin() and angle issue of two-dimensional arrays(tutorial)

2 years ago

I don't know where is your problem exactly, but looks more like a mathematic issue than a programming one.
If so, perhaps looking at http://en.wikipedia.org/wiki/Trigonometric_functions or some other tutorial can help.

burakkaan

Re: sin() and angle issue of two-dimensional arrays(tutorial)

2 years ago

thank you for helping i see 127 +- 127 issue now.
i have studied physics in high school and in uni. so i know trigonometry :) however still i couldn't understand what gives the 45 degree angle to this float, because i dont see sind(45)=0.71 and worse even though i have examined the tutorial and understood almost the whole but i still can't to this moving colors effect non-angled (linearly).

PhiLho

Re: sin() and angle issue of two-dimensional arrays(tutorial)

2 years ago

Ah, sorry! But we have lot of young people around and your message made me think you were stopping on sin() concept.
Not sure what to make out of your sin(45). Note that angle is in radian, not in degrees.
The trick in the code is the initialization of the angle to i+j which varies between 0 and 20.
If you want a linear effect, init with i for vertical lines, with j for horizontal lines.

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