To implement GLSurfaceView.Renderer, there’re 3 methods you must override:
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Here I’m going to show you how to draw a pentagon with OpenGL ES 2.0.įirst of all, declare OpenGL ES use in your AndroidManifest.xml :Īnd then implement both a GLSurfaceView and a GLSurfaceView.Renderer.Ĭhoosing a Global Software Development Partner to Accelerate Your Digital Strategy Ok, enough said, it’s time to do some real work. After getting the screen coordinates, we then can make these coordinates into pixels in screen, so we can actually see the content in the screen. To handle that, we need to do a Viewport Transformation to transform NDC coordinates into screen coordinates.
The language shader use is called GLSL, full name is OpenGL Shader Language, it’s a C like language.Īnother important knowledge in OpenGL is Graphics Pipeline. There are two types of shader, Vertex Shader and Fragment Shader. They are used to describe how to render the graphics. Shaders played a very important role in this process as you can see in the figure. So rasterization is actually a process of generating fragments. Rasterization is a process to map point, line or triangle into pixels on the screen, every mapping area is called a fragment. To understand the fragment better, we need to know about Rasterization. And fragments corresponding to pixels, usually a fragment is a pixel, but in some high resolution devices, a fragment may have more pixels. All graphics starts with vertex, a list of vertices can form a piece of graph. There’re two basic ideas in OpenGL, vertex and fragment.
In Android platform, several versions of the OpenGL ES API are supported, but why OpenGL ES 2.0? Because it does a great job both in compatibility and performance, you can check it here. OpenGL ES a flavor or subset of the OpenGL specification, it’s intended for embedded devices like smart phones, PDA and game consoles. It’s a abbreviation for Open Graphics Library for Embedded Systems. Well, one way to do that is through OpenGL ES. And you may wonder how do app developers build all those complex graphics and animations in a game. The performance of your smart phone’s GPU is important, especially when you are playing 3D games. Today most android devices in the market has a GPU, we all know that it’s a hardware unit for processing 3D graphics.