Drawing graphics with 3D enhancement Tips (iii)----triangular elements Trangle

1.

Glbegin (Gl_trangles);

........

Glend ();

2. Polygon Wrapping Direction: counterclockwise and clockwise positive and negative

Glfront (GL_CCW) and Glfront (GL_CW);

3. Triangle Belt

Glbegin (Gl_trangle_strip);

.......

Glend ();

4. Triangular fan

Glbegin (Gl_trangle_fan);

.......

Glend ();

Example:

//TRANGLE.cpp: Defines the entry point of the console application. //#include"stdafx.h"#include<GL\glut.h>#include<math.h>#definePI 3.14glfloat Range=100.0f ;BOOLdepth_test=false;BOOLCull_face=false;BOOLoutline_back=false;StaticGlfloat xrot=0.0f;StaticGlfloat yrot=0.0f;BOOLstop_depthtest=false;voidInit () {Glclearcolor (0.0f,0.0f,0.0f,1.0f);    Glfrontface (GL_CW); //Monotone ColoringGlshademodel (Gl_flat);}voidChangesize (intWinth) {    if(h==0) {h=1; } glviewport (0,0, w,h);    Glmatrixmode (gl_projection);    Glloadidentity (); if(w<=h) {Glortho (-range,range,-range*h/w,range*h/w,-Range,range); }    Else{Glortho (-range*w/h,range*w/h,-range,range,-Range,range);    } glmatrixmode (Gl_modelview); Glloadidentity ();}voidMyMenu (intvalue) {    Switch(value) { Case 1: Depth_test=!depth_test;  Break;  Case 2: Cull_face=!Cull_face;  Break;  Case 3: Outline_back=!Outline_back;  Break;  Case 4: Stop_depthtest=true; default:         Break; }}voidMyspecialkey (intKeyintXinty) {    if(key==glut_key_left) {Yrot-=5.0f; }    if(key==glut_key_right) {Yrot+=5.0f; }    if(key==glut_key_up) {Xrot-=5.0f; }    if(key==Glut_key_down) {Xrot+=5.0f; }    if(xrot>355.0f) {Xrot=0.0f; }    if(xrot<=-5.0f) {Xrot=355.0f; }    if(yrot>355.0f) {Yrot=0.0f; }    if(yrot<=-5.0f) {Yrot=355.0f; } glutpostredisplay ();}voidMydisplay () {Glint color=1; Glfloat Angle=0.0f;    Glfloat x, y; Glclear (Gl_color_buffer_bit|gl_depth_buffer_bit); if(depth_test) {glenable (gl_depth_test); }    Else{gldisable (gl_depth_test); }        if(cull_face) {glenable (gl_cull_face);    Glcullface (Gl_back); }    Else{gldisable (gl_cull_face); }    if(stop_depthtest) {gldisable (gl_depth_test); }    if(outline_back) {glpolygonmode (gl_back,gl_line); }    Else{glpolygonmode (Gl_back,gl_fill);    } Glpushmatrix (); Glrotatef (Xrot,1.0f,0.0f,0.0f); Glrotatef (Yrot,0.0f,1.0f,0.0f);    Glbegin (Gl_triangle_fan); glvertex3f (0.0f,0.0f,75.0f);  for(angle =0; angle<pi*2; angle+= (pi/8) ) {x=50.0f*cos (angle); Y=50.0f*sin (angle); if((color%2)==0) {glcolor3f (0.0f,1.0f,0.0f); }        Else{glcolor3f (1.0f,0.0f,0.0f); } Color++; glvertex3f (x, Y,0.0f);    } glend ();    Glbegin (Gl_triangle_fan); glvertex3f (0.0f,0.0f,0.0f);  for(angle =0; angle<pi*2; angle+= (pi/8) ) {x=50.0f*cos (angle); Y=50.0f*sin (angle); if((color%2)==0) {glcolor3f (0.0f,1.0f,0.0f); }        Else{glcolor3f (1.0f,0.0f,0.0f); } Color++; glvertex3f (x, Y,0.0f);    } glend ();    Glpopmatrix (); Glutswapbuffers ();}intMainintargcChar**argv) {Glutinit (&argc,argv); Glutinitdisplaymode (Glut_rgb| glut_double|glut_depth); Glutinitwindowposition ( -, -); Glutinitwindowsize ( -, -); Glutcreatewindow ("Trangle");    Init ();    Glutdisplayfunc (Mydisplay);        Glutreshapefunc (changesize);    Glutcreatemenu (MyMenu); Glutaddmenuentry ("Depth Test",1); Glutaddmenuentry ("Cullface",2); Glutaddmenuentry ("Outline Back",3); Glutaddmenuentry ("STOP depthtest",4);    Glutattachmenu (Glut_right_button);    Glutspecialfunc (Myspecialkey); Glutmainloop ();}

1. In-depth testing

2. Hide Face Removal

3. Wireframe mode: Glpoloygonmodel (Glenum Face,gl_line/gl_fill);

4. Shading Modes Glshademodel (Gl_flat) and Glshademodel (Gl_smooth);

Drawing graphics with 3D enhancement Tips (iii)----triangular elements trangle