Getting colour of pixel underneath mouse position

[darekg11]

I can't find any function that allows me to get r,g,b from current pixel. I might just not see it in documentation, any tip would be appreciated.

[Laurent]

There's no such function. Reading drawn pixels is extremely expensive (it must go all the way back from the GPU to the CPU). Why do you want to do that?

[darekg11]

In my game I would like to use isometric titles.
So first I load it, use mask on it to hide pink background so it will be transparent and I want to check if my mouse cursor is over title(by checking if color under the mosue is different than black) or over background (black)

[Laurent]

Reading the screen is possible (window.capture()) but strongly disadvised for this kind of computation, you should not rely on what you've drawn, but rather create and use your own optimized data structure for these tests.

[darekg11]

I see, I will figure something else. Thank You.

[Nexus]

You could just create a bitfield using std::vector<bool>, std::bitset or boost::dynamic_bitset.

Or a std::vector<BiggerIntegralType> and take care of the bit operations yourself.

[darekg11]

You mean like during loading of map create 800x600 array of bools and for each pixel assign true or false depending on color and then comparing mouse coordinates with according array value? If so that's really good idea. I will try it out, thank You.

[Nexus]

Yes, but don't use raw arrays, rather one of the data structures from my last post. They'll do the whole work for you and are optimized (either towards memory consumption or speed).