Many visual applications today, from simple games to advanced engineering, use OpenGL (Open Graphics Library) and OpenGL ES (OpenGL for Embedded Systems) as their graphics rendering API. These APIs provide a cross-platform, portable and high-performance graphics programming solution, supporting a large number of different types of devices and operating systems.
In this blog, we will gain an in-depth understanding of the basics of OpenGL and OpenGL ES, including their development history, core features, basic concepts, and more.
What is OpenGL?
OpenGL is an open standard graphics API originally developed by Silicon Graphics and released in 1992. The goal of OpenGL is to provide a general, scalable, cross-platform and high-performance image rendering solution, so that programmers can easily create complex 3D scenes and perform interactive operations.
OpenGL is optimized for different platforms, operating systems and hardware, so it is very suitable for developing programs with advanced 3D graphics requirements, such as CAD, virtual reality, games, etc.
What is OpenGL ES?
OpenGL ES was originally proposed for embedded devices, including smart phones, tablet PCs, and handheld game consoles. OpenGL ES is a subset of OpenGL, which provides a lightweight, portable 3D graphics API solution.
Since many embedded devices have relatively small video memory and processing power, OpenGL ES emphasizes simplifying and standardizing the API as much as possible in order to run efficiently in resource-constrained environments. OpenGL ES has become a widely adopted open standard and is considered one of the best choices for embedded systems.
Core features of OpenGL and OpenGL ES
Both OpenGL and OpenGL ES have the following core features:
- State machine-based: Their graphics rendering process is based on a state machine, and each operation is a modification of the current state.
- Programmable shader: This is the core component of OpenGL and OpenGL ES, and supports multiple shader types such as vertex shader and fragment shader.
- Matrix operation: Matrix operation is a commonly used graphics transformation technology. OpenGL and OpenGL ES provide many matrix operation functions, such as translation, scaling, rotation, etc.
- Graphics data: OpenGL and OpenGL ES use triangles to represent all graphics. Before drawing, vertex data needs to be assigned to the buffer.
Basic concepts of OpenGL and OpenGL ES
shader
Shaders are one of the most important components in OpenGL and OpenGL ES. A shader is a program that can be executed on the GPU to process each vertex and fragment. A shader usually consists of two parts: one part specifies the data type and sequence of input to the shader, and the other part is the code that performs the actual computation.
triangle
In OpenGL and OpenGL ES, all graphics are represented by triangles. Triangles are a simple, predictable, and efficient way to describe complex shapes. Triangles have a definite area and are guaranteed not to have any gaps or overlaps between two adjacent triangles.
texture
Textures refer to 2D or 3D images that are mapped onto triangular surfaces to enhance visual effects. Textures can be color images, grayscale images, or arbitrary image formats. Textures are often used to simulate surface details such as wood or stone.
buffer object
A buffer object is a mechanism for storing graphics data, including data such as vertices, indices, and textures. Using buffer objects can improve graphics rendering performance and reduce the amount of data transfer between the CPU and GPU.
in conclusion
This blog introduces the basics of OpenGL and OpenGL ES, which are necessary for developing advanced 3D graphics applications. Hopefully, after mastering this knowledge, you can better understand and apply OpenGL and OpenGL ES to create more complex and interesting 3D graphics applications.