Creating a color palette


I want to create a color palette for my painting program. Its just some kind of polygon with all colors on it and I should be able to select based on the intersected color.Can someone help me how to do this pls.

Thanks & Regards

Can’t you use the colour palettes included with GUI libraries?

gamedev90, you can use glReadPixels() on the pixel at mouse position, you will be able to read its exact color.