3/18/2024 0 Comments Opengl load texture png![]() ![]() That’s the only way I know of to load an image file AND maintaining platform independence. We will load this image: (Right-click to save as MyImage01.jpg, 20,123 bytes) This is generally done in two steps: Load image from the disk into RAM. This guide will have us load an image file from disk and display it in a Dear ImGui window. load important data from the file (height, width, bpp, etc.) skip to the data (always at the end of the header info) copy the data to memory. repeat from step 4 until end of file or end of allocated memory reached Because this is such a recurring issue for Dear ImGui users, we are providing a guide here.swap red and blue values (can be tricky in 15/16 bit formats).if data type is order specific (*), and system is big endian, swap byte order.get important information (include palette for 8 bit files).This is becoming really complicated, but if you need platform independance, it’s unfortunately necessary.Įven with all of these ideas, it’s not hard to write a bitmap and/or targa file loader: You’ll have to swap the dat around to reach 0bbbbbgg gggrrrrr format. On big endian systems, the short will come in like this: gggrrrrr 0bbbbbgg, where each letter represents a bit of the color. Using this format will only work on little endian systems. For example, 15 bit color stores a pixel as one short value, where the highest bit is never used, and the lower bits are blue, green, and red (5 bits each). Also, be wary of different pixel formats. The latter is less reliable since some systems will not have extension necessary to understand BGR and BRGA formats. Bitmap and Targa files store pixel data in the sequence BGR or BGRA (blue, green, red, alpha), but OpenGL wants the data in the form RGB or RGBA (red, green, blue, alpha.) There are two ways around this: you can convert it yourself, or tell OpenGL to. Unfortunately, this works very bad under OS X, so i decided not to use DevIL at all, and rewrite the respective parts of the application using another library. I have to use existing code which uses the DevIL library for loading JPG and PNG textures. Step 5 will give you headaches until you really understand it. i am writing an SDL / OpenGL application that runs under OSX. skip to the data (always at the end of the header info).load important data from the file (height, width, bpp, etc.).I made sure the image was in the folder containing the project file. I would like the image to appear behind the face I drew. The code looks right but the image is not uploading. The only advantage between them is Targa images can carry with it an additional alpha channel, which allows for some neat blending effects. png image using SOIL onto a face I drew using geometric primitives. Bitmap and Targa images are almost identical in the way they store data. ![]()
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