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#include <stdio.h>
#include <stdlib.h>
#include <GL/glut.h>
#define CHECK_ERROR(str) \
{ \
GLenum error; \
if(error = glGetError()) \
printf("GL Error: %s (%s)\n", gluErrorString(error), str); \
}
int winWidth = 512;
int winHeight = 512;
GLboolean smooth = GL_FALSE;
GLboolean dblbuf = GL_TRUE;
GLfloat objangle[2] = {0.f, 0.f};
GLfloat scale = 1.f;
int active;
enum {X, Y, Z};
enum {OBJ_ANGLE, OBJ_SCALE};
enum {NOLIST, PLANE}; /* display lists */
/* load data structure from file */
enum {VERTS, END};
void
reshape(int wid, int ht)
{
winWidth = wid;
winHeight = ht;
glViewport(0, 0, wid, ht);
}
void
motion(int x, int y)
{
switch(active)
{
case OBJ_ANGLE:
objangle[X] = (x - winWidth/2) * 360./winWidth;
objangle[Y] = (y - winHeight/2) * 360./winHeight;
glutPostRedisplay();
break;
case OBJ_SCALE:
scale = x * 5./winWidth;
objangle[Y] = (y - winHeight/2) * 360./winHeight;
glutPostRedisplay();
break;
}
}
void
mouse(int button, int state, int x, int y)
{
if(state == GLUT_DOWN)
switch(button)
{
case GLUT_LEFT_BUTTON: /* rotate the object */
active = OBJ_ANGLE;
motion(x, y);
break;
case GLUT_RIGHT_BUTTON: /* scale the object */
active = OBJ_SCALE;
motion(x, y);
break;
}
}
/* ARGSUSED1 */
void key(unsigned char key, int x, int y)
{
switch(key)
{
case 's': /* toggle line smoothing */
if(smooth)
{
glDisable(GL_LINE_SMOOTH);
glDisable(GL_BLEND);
smooth = GL_FALSE;
printf("Turn off OpenGL line smoothing\n");
}
else
{
glEnable(GL_LINE_SMOOTH);
glEnable(GL_BLEND);
printf("Turn on OpenGL line smoothing\n");
smooth = GL_TRUE;
}
glutPostRedisplay();
break;
case '\033':
exit(0);
break;
case '?':
case 'h':
case 'H':
default:
fprintf(stderr, "Keyboard commands:\n\n"
"s - toggle smooth line mode\n");
break;
}
}
void
loader(char *fname)
{
FILE *fp;
GLfloat x, y, z;
int state = END;
int read;
fp = fopen(fname, "r");
if (!fp) {
printf("can't open file %s\n", fname);
exit(1);
}
glNewList(PLANE, GL_COMPILE);
while(!feof(fp))
{
switch(state)
{
case END:
read = fscanf(fp, " v");
if(read < 0) /* hit eof */
break;
state = VERTS;
glBegin(GL_LINE_STRIP);
break;
case VERTS:
read = fscanf(fp, " %f %f %f", &x, &y, &z);
if(read == 3)
glVertex3f(x, y, z);
else
{
fscanf(fp, " e");
glEnd();
state = END;
}
break;
}
}
glEndList();
fclose(fp);
}
void redraw(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
glRotatef(objangle[X], 0.f, 1.f, 0.f); /* rotate object */
glRotatef(objangle[Y], 1.f, 0.f, 0.f);
glScalef(scale, scale, scale);
glCallList(PLANE);
glPopMatrix();
if(dblbuf)
glutSwapBuffers();
else
glFlush();
CHECK_ERROR("OpenGL Error in redraw()");
}
void main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitWindowSize(winWidth, winHeight);
if(argc > 1)
{
char *args = argv[1];
GLboolean done = GL_FALSE;
while(!done)
{
switch(*args)
{
case 's': /* single buffer */
printf("Single Buffered\n");
dblbuf = GL_FALSE;
break;
case '-': /* do nothing */
break;
case 0:
done = GL_TRUE;
break;
}
args++;
}
}
if(dblbuf)
glutInitDisplayMode(GLUT_RGBA|GLUT_DOUBLE);
else
glutInitDisplayMode(GLUT_RGBA);
(void)glutCreateWindow("load and draw a wireframe image");
glutDisplayFunc(redraw);
glutReshapeFunc(reshape);
glutKeyboardFunc(key);
glutMotionFunc(motion);
glutMouseFunc(mouse);
glMatrixMode(GL_PROJECTION);
glOrtho(-1., 1., -1., 1., -5., 5.);
glMatrixMode(GL_MODELVIEW);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
loader("data/f15.data");
CHECK_ERROR("OpenGL Error in main()");
key('?', 0, 0); /* print usage message */
glutMainLoop();
}
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