// // This code was created by Jeff Molofee '99 (ported to Linux/GLUT by Richard Campbell '99) // // If you've found this code useful, please let me know. // // Visit me at www.demonews.com/hosted/nehe // (email Richard Campbell at ulmont@bellsouth.net) // #include // Header File For The GLUT Library #include // Header File For The OpenGL32 Library #include // Header File For The GLu32 Library #include // Header File For sleeping. #include #include #include #include #include /* ASCII code for the escape key. */ #define ESCAPE 27 #define UPDATE_THRESHOLD 4 #define SLEEP_INTERVAL 100000 /* microseconds */ #define SYSFS_POSITION_FILE "/sys/devices/platform/hdaps/position" #define BUF_LEN 32 #define WIDTH 1024 #define HEIGHT 768 #define GRAVITY 10 /* The number of our GLUT window */ int window; static int val_x = 0; static int val_y = 0; static int rest_x; static int rest_y; static double vel_x = 0.0; static double vel_y = 0.0; static double pos_x = 0.0; static double pos_y = 2.0; static int read_position (int *x, int *y) { char buf[BUF_LEN]; int fd, ret; fd = open (SYSFS_POSITION_FILE, O_RDONLY); if (fd < 0) { perror ("open"); return fd; } ret = read (fd, buf, BUF_LEN); if (ret < 0) { perror ("read"); goto out; } else if (ret == 0) { fprintf (stderr, "error: unexpectedly read zero!\n"); ret = 1; goto out; } ret = 0; if (sscanf (buf, "(%d,%d)\n", x, y) != 2) ret = 1; out: if (close (fd)) perror ("close"); return ret; } /* A general OpenGL initialization function. Sets all of the initial parameters. */ void InitGL(int Width, int Height) /* We call this right after our OpenGL window is created. */ { glClearColor(0.0f, 0.0f, 0.0f, 0.0f); /* This Will Clear The Background Color To Black */ glClearDepth(1.0); /* Enables Clearing Of The Depth Buffer */ glDepthFunc(GL_LESS); /* The Type Of Depth Test To Do */ glEnable(GL_DEPTH_TEST); /* Enables Depth Testing */ glShadeModel(GL_SMOOTH); /* Enables Smooth Color Shading */ glMatrixMode(GL_PROJECTION); glLoadIdentity(); // Reset The Projection Matrix glMatrixMode (GL_PROJECTION); glLoadIdentity (); gluPerspective (45.0f, (GLfloat)WIDTH / (GLfloat)HEIGHT, 0.1f, 100.0f); glMatrixMode (GL_MODELVIEW); glLoadIdentity (); glTranslated (0.0, -0.5, -4.0); } /* The function called when our window is resized (which shouldn't happen, because we're fullscreen) */ void ReSizeGLScene(int Width, int Height) { if (Height==0) /* Prevent A Divide By Zero If The Window Is Too Small */ Height=1; glViewport(0, 0, Width, Height); /* Reset The Current Viewport And Perspective Transformation */ glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f); glMatrixMode(GL_MODELVIEW); } /* The main drawing function. */ static void DrawGLScene() { calc_position(); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); /* Clear The Screen And The Depth Buffer */ glPushMatrix (); glLoadIdentity (); glTranslatef(0.0f,0.0f,-6.0f); /* Move Left 1.5 Units And Into The Screen 6.0 */ glTranslatef(pos_x,pos_y,0.0f); /* Move to pos_x and pos_y */ /* draw a square (quadrilateral) */ glBegin(GL_QUADS); // start drawing a polygon (4 sided) glVertex3f(-0.2f, 0.2f, 0.0f); // Top Left glVertex3f( 0.2f, 0.2f, 0.0f); // Top Right glVertex3f( 0.2f,-0.2f, 0.0f); // Bottom Right glVertex3f(-0.2f,-0.2f, 0.0f); // Bottom Left glEnd(); // done with the polygon // swap buffers to display, since we're double buffered. glPopMatrix (); glutSwapBuffers(); } /* The function called whenever a key is pressed. */ void keyPressed(unsigned char key, int x, int y) { /* avoid thrashing this procedure */ usleep(100); /* If escape is pressed, kill everything. */ if (key == ESCAPE) { /* shut down our window */ glutDestroyWindow(window); /* exit the program...normal termination. */ exit(0); } } static void update_scene (void) { int ret, x, y, do_update = 0; ret = read_position (&x, &y); if (ret) exit(EXIT_FAILURE); x -= rest_x; y -= rest_y; /* only update if we surpass our threshold, to minimize jitter ... */ if (abs (x - val_x) > UPDATE_THRESHOLD) { val_x = x; do_update = 1; } if (abs (y - val_y) > UPDATE_THRESHOLD) { val_y = y; do_update = 1; } /* ... or, if we are within our threshold of zero, reset to zero */ if (abs (x) < UPDATE_THRESHOLD) { val_x = 0; do_update = 1; } if (abs (y) < UPDATE_THRESHOLD) { val_y = 0; do_update = 1; } DrawGLScene(); usleep (SLEEP_INTERVAL); } void calc_position(void) { double g_x = GRAVITY * sin(val_x*0.01122); double g_y = -GRAVITY * cos(val_x*0.01122); double del_t = (double)SLEEP_INTERVAL / 1.0e6; vel_x += (g_x - vel_x) * del_t; vel_y += (g_y - vel_y) * del_t; pos_x += vel_x * del_t; if (pos_x > 3.0) { pos_x = 3.0; vel_x = -vel_x; } else if (pos_x < -3.0) { pos_x = -3.0; vel_x = -vel_x; } pos_y += vel_y * del_t; if (pos_y > 2.0) { pos_y = 2.0; vel_y = -vel_y; } else if (pos_y < -2.0) { pos_y = -2.0; vel_y = -vel_y; } } int main(int argc, char **argv) { int ret; ret = read_position (&rest_x, &rest_y); if (ret) return 1; /* Initialize GLUT state - glut will take any command line arguments that pertain to it or X Windows - look at its documentation at http://reality.sgi.com/mjk/spec3/spec3.html */ glutInit(&argc, argv); /* Select type of Display mode: Double buffer RGBA color Alpha components supported Depth buffer */ glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_ALPHA | GLUT_DEPTH); /* get a WIDTH x HEIGHT window */ glutInitWindowSize(WIDTH, HEIGHT); /* the window starts at the upper left corner of the screen */ glutInitWindowPosition(0, 0); /* Open a window */ window = glutCreateWindow("Thinkpad Accelerometer Test"); /* Register the function to do all our OpenGL drawing. */ glutDisplayFunc(&update_scene); /* Even if there are no events, redraw our gl scene. */ glutIdleFunc(&update_scene); /* Register the function called when our window is resized. */ glutReshapeFunc(&update_scene); /* Register the function called when the keyboard is pressed. */ glutKeyboardFunc(&keyPressed); /* Initialize our window. */ InitGL(WIDTH, HEIGHT); /* Start Event Processing Engine */ glutMainLoop(); return 1; }