OpenGL¶

key task: 将三维的物体投影到二维的屏幕上

OpenGL toolchain¶

• OpenGL #include <GL/gl.h>
• Platform-independent “core” library
• GLU #include <GL/glu.h>
• an auxiliary library that handles a variety of graphics accessory functions
• GLUT #include <GL/glut.h>
• an auxiliary library that handles window creation, OS system calls (mouse buttons, movement, keyboard, etc.)

Three States in OpenGL + Define Objects in World Space + Set Modeling and Viewing Transformations + Render the Scene

How it work¶

• OpenGL is a state machine
• Give orders to set the current state of any one of its internal variables, or to query its current status
• The current state won’t change until you explicitly specify a new value
• if you set the current color to Red, everything you draw will be painted Red until you change the color explicitly
• Each of the system’s state variables has a default value

OpenGL Primitives¶

• GL_POINTS
• GL_LINES
• GL_LINE_STRIP
• GL_LINE_LOOP
• GL_TRIANGLES
• GL_QUADS
• GL_POLYGON
• GL_TRIANGLE_STRIP
• GL_TRIANGLE_FAN
• GL_QUAD_STRIP