GLFW:Tutorials:Keyreader
From GPWiki
Let's focus on reading from the Keyboard.
First, we need to include the header for glfw to be able to use it
- include <stdio.h>
- include <math.h>
- include <GL/glfw.h>
Next we will need some global variables. You will see later what they are used for.
int running;
int keyrepeat = 0;
int systemkeys = 1;
After that we will setup a main function. Most interesting for us is the key callback function. As you can see by using glfwSetKeyCallback(keyhandler); we define the function keyhandler as function that examines what has happend to the key.
int main( void )
{
int width, height; double t;
// Initialise GLFW glfwInit();
// Open OpenGL window
if( !glfwOpenWindow(250, 100, 0,0,0,0, 0,0, GLFW_WINDOW ) )
{
glfwTerminate();
return 0;
}
// Set key callback function glfwSetKeyCallback( keyhandler );
// Set tile glfwSetWindowTitle( "Press some keys!" );
// Main loop
running = GL_TRUE;
while( running )
{
// Get time and mouse position
t = glfwGetTime();
// Get window size (may be different than the requested size)
glfwGetWindowSize( &width, &height );
height = height > 0 ? height : 1;
// Set viewport
glViewport( 0, 0, width, height );
// Clear color buffer
glClearColor( (GLfloat)(0.5+0.5*sin(3.0*t)), 0.0f, 0.0f, 0.0f);
glClear( GL_COLOR_BUFFER_BIT );
// Swap buffers
glfwSwapBuffers();
// Check if the window was closed
running = running && glfwGetWindowParam( GLFW_OPENED );
}
// Close OpenGL window and terminate GLFW glfwTerminate();
return 0;
}
So last but not least we will set up a very simple handler function that knows what do to when a key has been pressed (otherwise it does nothing). You can see that R and S have special functions. R turns on and off repeating of keys while holding the button down. S turns on and off the system keys.
void GLFWCALL keyhandler( int key, int action )
{
if( action != GLFW_PRESS )
{
return;
}
switch( key )
{
case GLFW_KEY_ESC:
printf( "ESC => quit program\n" );
running = GL_FALSE;
break;
case GLFW_KEY_F1:
case GLFW_KEY_F2:
case GLFW_KEY_F3:
case GLFW_KEY_F4:
case GLFW_KEY_F5:
case GLFW_KEY_F6:
case GLFW_KEY_F7:
case GLFW_KEY_F8:
case GLFW_KEY_F9:
case GLFW_KEY_F10:
case GLFW_KEY_F11:
case GLFW_KEY_F12:
case GLFW_KEY_F13:
case GLFW_KEY_F14:
case GLFW_KEY_F15:
case GLFW_KEY_F16:
case GLFW_KEY_F17:
case GLFW_KEY_F18:
case GLFW_KEY_F19:
case GLFW_KEY_F20:
case GLFW_KEY_F21:
case GLFW_KEY_F22:
case GLFW_KEY_F23:
case GLFW_KEY_F24:
case GLFW_KEY_F25:
printf( "F%d\n", 1 + key - GLFW_KEY_F1 );
break;
case GLFW_KEY_UP:
printf( "UP\n" );
break;
case GLFW_KEY_DOWN:
printf( "DOWN\n" );
break;
case GLFW_KEY_LEFT:
printf( "LEFT\n" );
break;
case GLFW_KEY_RIGHT:
printf( "RIGHT\n" );
break;
case GLFW_KEY_LSHIFT:
printf( "LSHIFT\n" );
break;
case GLFW_KEY_RSHIFT:
printf( "RSHIFT\n" );
break;
case GLFW_KEY_LCTRL:
printf( "LCTRL\n" );
break;
case GLFW_KEY_RCTRL:
printf( "RCTRL\n" );
break;
case GLFW_KEY_LALT:
printf( "LALT\n" );
break;
case GLFW_KEY_RALT:
printf( "RALT\n" );
break;
case GLFW_KEY_TAB:
printf( "TAB\n" );
break;
case GLFW_KEY_ENTER:
printf( "ENTER\n" );
break;
case GLFW_KEY_BACKSPACE:
printf( "BACKSPACE\n" );
break;
case GLFW_KEY_INSERT:
printf( "INSERT\n" );
break;
case GLFW_KEY_DEL:
printf( "DEL\n" );
break;
case GLFW_KEY_PAGEUP:
printf( "PAGEUP\n" );
break;
case GLFW_KEY_PAGEDOWN:
printf( "PAGEDOWN\n" );
break;
case GLFW_KEY_HOME:
printf( "HOME\n" );
break;
case GLFW_KEY_END:
printf( "END\n" );
break;
case GLFW_KEY_KP_0:
printf( "KEYPAD 0\n" );
break;
case GLFW_KEY_KP_1:
printf( "KEYPAD 1\n" );
break;
case GLFW_KEY_KP_2:
printf( "KEYPAD 2\n" );
break;
case GLFW_KEY_KP_3:
printf( "KEYPAD 3\n" );
break;
case GLFW_KEY_KP_4:
printf( "KEYPAD 4\n" );
break;
case GLFW_KEY_KP_5:
printf( "KEYPAD 5\n" );
break;
case GLFW_KEY_KP_6:
printf( "KEYPAD 6\n" );
break;
case GLFW_KEY_KP_7:
printf( "KEYPAD 7\n" );
break;
case GLFW_KEY_KP_8:
printf( "KEYPAD 8\n" );
break;
case GLFW_KEY_KP_9:
printf( "KEYPAD 9\n" );
break;
case GLFW_KEY_KP_DIVIDE:
printf( "KEYPAD DIVIDE\n" );
break;
case GLFW_KEY_KP_MULTIPLY:
printf( "KEYPAD MULTIPLY\n" );
break;
case GLFW_KEY_KP_SUBTRACT:
printf( "KEYPAD SUBTRACT\n" );
break;
case GLFW_KEY_KP_ADD:
printf( "KEYPAD ADD\n" );
break;
case GLFW_KEY_KP_DECIMAL:
printf( "KEYPAD DECIMAL\n" );
break;
case GLFW_KEY_KP_EQUAL:
printf( "KEYPAD =\n" );
break;
case GLFW_KEY_KP_ENTER:
printf( "KEYPAD ENTER\n" );
break;
case GLFW_KEY_SPACE:
printf( "SPACE\n" );
break;
case 'R':
keyrepeat = (keyrepeat+1) & 1;
if( keyrepeat )
{
glfwEnable( GLFW_KEY_REPEAT );
}
else
{
glfwDisable( GLFW_KEY_REPEAT );
}
printf( "R => Key repeat: %s\n", keyrepeat ? "ON" : "OFF" );
break;
case 'S':
systemkeys = (systemkeys+1) & 1;
if( systemkeys )
{
glfwEnable( GLFW_SYSTEM_KEYS );
}
else
{
glfwDisable( GLFW_SYSTEM_KEYS );
}
printf( "S => System keys: %s\n", systemkeys ? "ON" : "OFF" );
break;
default:
if( key > 0 && key < 256 )
{
printf( "%c\n", (char) key );
}
else
{
printf( "???\n" );
}
break;
}
fflush( stdout );
}
That's it. You just wrote a program to handle keys.
Source code
- You can download the source code for this tutorial here.
