Tom Kelliher, CS 320
Feb. 18, 2005
Read paint.c
, Section 3.8.
Input devices and interaction introduction.
paint.c
Display lists and distributed computing.
Idea:
Example:
void renderString(GLdouble x, GLdouble y, void *font, char *text) { glRasterPos2d(x, y); while (text) { glutBitmapCharacter(font, *text); ++text; } }See man page for glutBitmapCharacter for list of available bitmap fonts. Example:
renderString(0.0, 0.0, GLUT_BITMAP_9_BY_15, "OpenGL rocks!");
Idea similar to font cache: display lists. Program example:
base = glGenLists(128); for(i=0;i<128;i++) { glNewList(base+i, GL_COMPILE); glutBitmapCharacter(GLUT_BITMAP_9_BY_15, i); glEndList(); } glListBase(base);Use:
// Dump time string into out. glRasterPos2i(ww-80, wh-15); // Window units = world units. glColor3f(0.0,0.0,0.0); glBegin(GL_QUADS); // Erase current time. glVertex2i(ww-80, wh-15); glVertex2i(ww, wh-15); glVertex2i(ww, wh); glVertex2i(ww-80, wh); glEnd(); glColor3f(1.0,1.0,1.0); glCallLists(strlen(out), GL_BYTE, out);Another example:
list = glGenLists(1) glNewList(list, GL_COMPILE); glBegin(GL_POLYGON); glVertex2f(...); ... glEnd(); glEndList(); ... glCallList(list);
Why do we use menus? --- What's the alternative?
int main(int argc, char** argv) { int c_menu, p_menu, f_menu; // ... c_menu = glutCreateMenu(color_menu); glutAddMenuEntry("Red",1); glutAddMenuEntry("Green",2); glutAddMenuEntry("Blue",3); glutAddMenuEntry("Cyan",4); glutAddMenuEntry("Magenta",5); glutAddMenuEntry("Yellow",6); glutAddMenuEntry("White",7); glutAddMenuEntry("Black",8); p_menu = glutCreateMenu(pixel_menu); glutAddMenuEntry("increase pixel size", 1); glutAddMenuEntry("decrease pixel size", 2); f_menu = glutCreateMenu(fill_menu); glutAddMenuEntry("fill on", 1); glutAddMenuEntry("fill off", 2); glutCreateMenu(right_menu); glutAddMenuEntry("quit",1); glutAddMenuEntry("clear",2); glutAttachMenu(GLUT_RIGHT_BUTTON); glutCreateMenu(middle_menu); glutAddSubMenu("Colors", c_menu); glutAddSubMenu("Pixel Size", p_menu); glutAddSubMenu("Fill", f_menu); glutAttachMenu(GLUT_MIDDLE_BUTTON); // ... }
void color_menu(int id) { if(id == 1) {r = 1.0; g = 0.0; b = 0.0;} else if(id == 2) {r = 0.0; g = 1.0; b = 0.0;} else if(id == 3) {r = 0.0; g = 0.0; b = 1.0;} else if(id == 4) {r = 0.0; g = 1.0; b = 1.0;} else if(id == 5) {r = 1.0; g = 0.0; b = 1.0;} else if(id == 6) {r = 1.0; g = 1.0; b = 0.0;} else if(id == 7) {r = 1.0; g = 1.0; b = 1.0;} else if(id == 8) {r = 0.0; g = 0.0; b = 0.0;} }
What's the problem here?
int pick(int x, int y) { y = wh - y; if(y < wh-ww/10) return 0; else if(x < ww/10) return LINE; else if(x < ww/5) return RECTANGLE; else if(x < 3*ww/10) return TRIANGLE; else if(x < 2*ww/5) return POINTS; else if(x < ww/2) return TEXT; else return 0; } void mouse(int btn, int state, int x, int y) { static int count; int where; static int xp[2],yp[2]; if(btn==GLUT_LEFT_BUTTON && state==GLUT_DOWN) { glPushAttrib(GL_ALL_ATTRIB_BITS); where = pick(x,y); glColor3f(r, g, b); if(where != 0) { count = 0; draw_mode = where; } else switch(draw_mode) { case(LINE): if(count==0) { count++; xp[0] = x; yp[0] = y; } else { glBegin(GL_LINES); glVertex2i(x,wh-y); glVertex2i(xp[0],wh-yp[0]); glEnd(); draw_mode=0; count=0; } break; case(RECTANGLE): if(count == 0) { count++; xp[0] = x; yp[0] = y; } else { if(fill) glBegin(GL_POLYGON); else glBegin(GL_LINE_LOOP); glVertex2i(x,wh-y); glVertex2i(x,wh-yp[0]); glVertex2i(xp[0],wh-yp[0]); glVertex2i(xp[0],wh-y); glEnd(); draw_mode=0; count=0; } break; case (TRIANGLE): switch(count) { case(0): count++; xp[0] = x; yp[0] = y; break; case(1): count++; xp[1] = x; yp[1] = y; break; case(2): if(fill) glBegin(GL_POLYGON); else glBegin(GL_LINE_LOOP); glVertex2i(xp[0],wh-yp[0]); glVertex2i(xp[1],wh-yp[1]); glVertex2i(x,wh-y); glEnd(); draw_mode=0; count=0; } break; case(POINTS): { drawSquare(x,y); count++; } break; case(TEXT): { rx=x; ry=wh-y; glRasterPos2i(rx,ry); count=0; } } glPopAttrib(); glFlush(); } }