can a bmp image format handle transparency
I am making this C++ program that has buttons, button containers, chat boxes, etc., and I want to wrap it around by textures.
I want to generate a smooth edge for all the rectangles I made, and I don't want vertex plotting method to do the work for it, since it consumes more CPU usage and not that looks pretty good, and I don't know if it can work with texture coordinates(i.e. glTexCoord(u, v) with glVertex2f(x, y) w/c should only be 4 since it is a quad)
I use to load textures using SDL_LoadBMP() w/c can load only a format of .bmp.(I'm not that sure because it says only LoadBMP there).
So my questions are:
can a .bmp format handle transparency? if so, how to do it?
can you show me some code samples using SOIL to load image of format .gif or any other formats that can handle image transparency?
can a quad handle an irregular/polygons shape like hexagon or star without drawing its background?
additional question
*how to import a primitive textbox that renders through c++ opengl so I can copy the texts there into clipboard? as for chatting session in my program.
I made my own library that draws the text using GL_POINTS and doesn't look good when resizing the window because the points were spread-out. It takes const char* for the text to avoid #include <*string*> because I want my program to be not dependent on core functions of C++.
So the better solution is to draw it using bitmaps.
Some suggest to draw it using images so I really need the transparency thing because I want it to draw using quad only.
Answer
Yes, the bitmap format does support transparency.
It depends on the compression method, the default RGB method supports 24-bit color, but BITFIELDS compression supports 32-bit color (24-bit + alpha channel).
You can read more at http://en.wikipedia.org/wiki/BMP_file_format
I am using it successfully in the Lime project, here is an implementation written in Haxe: https://github.com/openfl/lime/blob/4adb7d638d15612e2542ae3a0ef581a786d21183/src/lime/_internal/format/BMP.hx