Differences between P5 and PJS: isNaN(), g, try/catch

hamoid

Differences between P5 and PJS: isNaN(), g, try/catch

in Processing with Other Languages • 1 year ago

Hi, I've been switching between Processing and ProcessingJS often during the last days and I keep finding differences between them. Maybe you have some ideas about dealing with these:

isNaN(), a JavaScript function, is Float.isNaN() in Java. Float does not exist in JavaScript. How would you write code that uses isNaN() and is compatible with both? (isNaN stands for "is not a number")
In Java I can do myPImage.copy(g, ...) to copy from the main canvas into an image. But "g" does not exist in ProcessingJS. Is it doable? Is there a way to write compatible code? Or the only way is using pixels[]?

Try/catch is not documented in the ProcessingJS reference, but it seems to work. I thought I could try to use isNaN and if it fails, catch and use the other isNaN. The funny thing is that Processing (Java) does not let me run something with an error, so I can not even attempt to call isNaN() in the Java version.

Replies(2)

PhiLho

Re: Differences between P5 and PJS: isNaN(), g, try/catch

1 year ago

- Maybe you can create a Float array and put isNaN there.
- If you replace your PImage with a PGraphics, you can use get() to grab a portion of the sketch area, and image() to draw it on your buffer.
- try/catch is actually a valid JavaScript construct.

hamoid

Re: Differences between P5 and PJS: isNaN(), g, try/catch

1 year ago

Thanks for the ideas. This is what I was building: http://hamoid.com/processingjs/mindex/ (click checkbox + send)

I think I don't get the Float array idea.

I'm reading a CSV file, which is supposed to be full of float values. And I am building a float array out of those values. But sometimes there are errors. I don't know of a simple way of testing isNaN that works on both on JS and Java. I could make sure the number-string contains only numbers and a dot, but that would be slow.
I ended up using arrayCopy() to duplicate the pixels[] array. What I'm doing is loading an SVG map, rendering each region with a different color, saving that image to an array, and later using that array to know if the mouse is on top of one of the regions so I can show the name and highlight the region.
try/catch is valid JS code, but I didn't know if it was valid ProcessingJS code, because it's not on the reference.

My experiment is slow on Firefox and can be greatly optimized. It was part of a hackaton with journalists in Helsinki.