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I’ve implemented a plotting class that is currently capable of handling integer values only. I would like to get advice about techniques/mechanisms in order to handle floating numbers. Library used is GDI.
Thanks,
Adi
At some point, they need to be converted to integers to draw actual pixels.
Generally speaking, however, you do not want to just cast each float to int, and draw — you’ll almost certainly get a mess. Instead, you need/want to scale the floats, then round the scaled value to an integer. In most cases, you’ll want to make the scaling factor variable so the user can zoom in and out as needed.
Another possibility is to let the hardware handle most of the work — you could use OpenGL (for one example) to render your points, leaving them as floating point internally, and letting the driver/hardware handle issues like scaling and conversion to integers. This has a rather steep cost up-front (learning enough OpenGL to get it to do anything useful), but can have a fairly substantial payoff as well, such as fast, hardware-based rendering, and making it relatively easy to handle some things like scaling and (if you ever need it) being able to display 3D points as easily as 2D.
Edit:(mostly response to comment): Ultimately it comes down to this: the resolution of a screen is lower than the resolution of a floating point number. For example, a really high resolution screen might display 2048 pixels horizontally — that’s 11 bits of resolution. Even a single precision floating point number has around 24 bits of precision. No matter how you do it, reducing 24-bit resolution to 12-bit resolution is going to lose something — usually a lot.
That’s why you pretty nearly have to make your scaling factor variable — so the user can choose whether to zoom out and see the whole picture with reduced resolution, or zoom in to see a small part at high resolution.
Since sub-pixel resolution was mentioned: it does help, but only a little. It’s not going to resolve a thousand different items that map to a single pixel.