jgs SER332 Introduction to Graphics and Game Development Lecture 04: Callback Functions Javier Gonzalez-Sanchez [email protected] PERALTA 230U Office Hours: By appointment
Javier Gonzalez-Sanchez | SER332 | Spring 2018 | 7 jgs Double Buffering Double buffering is necessary for almost all OpenGL applications: § Render into back buffer § Swap buffers when finished rendering a frame: The old back buffer becomes the front buffer that is displayed. The old front buffer becomes the back buffer that is rendered into. What happens when you do not use double buffering? § flickering artifacts, tearing artifacts Commands: § glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE ); § glutSwapBuffers(); //instead of glFlush()
Javier Gonzalez-Sanchez | SER332 | Spring 2018 | 9 jgs Callback Functions § What is this? void (*func)(void) § GLUT uses callbacks to handle events Windows system invokes a particular procedure when an event of particular type occurs. MOST IMPORTANT: display event. It is signaled when window first displays and whenever portions of the window reveals from blocking window glutDisplayFunc(void (*func)(void)) registers the display callback function
Javier Gonzalez-Sanchez | SER332 | Spring 2018 | 10 jgs Callbacks Functions § glutDisaplyFunc(void (*func)(void)) whenever GLUT decides to redisplay the window, the registered callback is executed. § glutReshapeFunc(void (*func)(int w, int h)) indicates what action should be taken when the window is resized. § glutKeyboardFunc(void (*func)(unsigned char key, int x, int y)) glutMouseFunc(void (*func)(int button, int state, int x, int y)) glutSpecialFunc(void (*func)(unsigned char key, int x, int y)) allow you to link a keyboard key or a mouse button with a routine that's invoked when the key or mouse button is pressed or released.
Javier Gonzalez-Sanchez | SER332 | Spring 2018 | 11 jgs Callbacks Functions § glutMotionFunc(void (*func)(int x, int y)) registers a routine to call back when the mouse is moved while a mouse button is also pressed. § glutIdleFunc(void (*func)(void)) registers a function that's to be executed if no other events are pending – use for animation or continuous update
Javier Gonzalez-Sanchez | SER332 | Spring 2018 | 16 jgs Key Modifiers int glutGetModifiers(void) To detect if any modifier key is pressed § GLUT_ACTIVE_SHIFT SHIFT key § GLUT_ACTIVE_CTRL CTRL key § GLUT_ACTIVE_ALT ALT key
Javier Gonzalez-Sanchez | SER332 | Spring 2018 | 18 jgs Special Keys § GLUT_KEY_F1 F1 function key § … § GLUT_KEY_F12 F12 function key § GLUT_KEY_LEFT Left function key § GLUT_KEY_RIGHT Up function key § GLUT_KEY_UP Right function key § GLUT_KEY_DOWN Down function key § GLUT_KEY_PAGE_UP Page Up function key § GLUT_KEY_PAGE_DOWN Page Down function key § GLUT_KEY_HOME Home function key § GLUT_KEY_END End function key § GLUT_KEY_INSERT Insert function key
Javier Gonzalez-Sanchez | SER332 | Spring 2018 | 21 jgs Mouse Passive Motion Callback glutPassiveMotionFunc( myMousePMotion ); § Almost as same function as the glutMotionFunc(); § The (Active) motion callback is called when the mouse moves within the window while one or more mouse buttons are pressed. § The Passive motion callback is called when the mouse moves within the window while no mouse buttons are pressed.
Javier Gonzalez-Sanchez | SER332 | Spring 2018 | 22 jgs Example 2 § Change color with the arrow keys § Move the triangles with the mouse (left click) § Move and shake with the mouse (right click)
Javier Gonzalez-Sanchez | SER332 | Spring 2018 | 23 jgs Reading OpenGL command syntax § Red Book(pdf): ch1 p17 – p18 Understand OpenGL’s state machine model § Red Book(pdf):ch1 p18 Understand OpenGL’s client server model § An example, glFlush, Red Book(pdf): ch2 p32 § Think about the differences between glFlush, glFinish, glutSwapBuffers. To better understand glFinish, think if you want to measure the exact rendering time of one frame on GPU.
Javier Gonzalez-Sanchez | SER332 | Spring 2018 | 24 jgs Reading Animation & Double buffering § Red Book(pdf): ch1 p24, explains double buffering and glutSwapBuffers GLUT (important) § Red Book(pdf): ch1 p21 - p28 § Hearn Baker ch6 p307 – p34, similar as above but in more details § Red Book Appendix D § Example 1-2, Example 1-3 (Animation) § Glut.h will show you the technical details
jgs SER332 Introduction to Graphics Javier Gonzalez-Sanchez [email protected] Spring 2018 Disclaimer. These slides can only be used as study material for the class SER332 at ASU. They cannot be distributed or used for another purpose.
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