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/**
* Test glPolygonMode.
* A tri-strip w/ two tris is drawn so that the first tri is front-facing
* but the second tri is back-facing.
* Set glPolygonMode differently for the front/back faces
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glut.h>
static int Win;
static GLfloat Zrot = 0;
static GLboolean FrontFillBackUnfilled = GL_TRUE;
static GLboolean Lines = GL_TRUE;
static void
Draw(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
if (FrontFillBackUnfilled) {
if (Lines) {
printf("FrontMode = FILL, BackMode = LINE\n");
glPolygonMode(GL_BACK, GL_LINE);
}
else {
printf("FrontMode = FILL, BackMode = POINT\n");
glPolygonMode(GL_BACK, GL_POINT);
}
glPolygonMode(GL_FRONT, GL_FILL);
}
else {
if (Lines) {
printf("FrontMode = LINE, BackMode = FILL\n");
glPolygonMode(GL_FRONT, GL_LINE);
}
else {
printf("FrontMode = POINT, BackMode = FILL\n");
glPolygonMode(GL_FRONT, GL_POINT);
}
glPolygonMode(GL_BACK, GL_FILL);
}
glPushMatrix();
glRotatef(Zrot, 0, 0, 1);
glBegin(GL_TRIANGLE_STRIP);
glVertex2f(-1, 0);
glVertex2f( 1, 0);
glVertex2f(0, 1);
glVertex2f(0, -1);
glEnd();
glPopMatrix();
glutSwapBuffers();
}
static void
Reshape(int width, int height)
{
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0.0, 0.0, -15.0);
}
static void
Key(unsigned char key, int x, int y)
{
const GLfloat step = 3.0;
(void) x;
(void) y;
switch (key) {
case 'p':
FrontFillBackUnfilled = !FrontFillBackUnfilled;
break;
case 'l':
Lines = !Lines;
break;
case 'z':
Zrot -= step;
break;
case 'Z':
Zrot += step;
break;
case 27:
glutDestroyWindow(Win);
exit(0);
break;
}
glutPostRedisplay();
}
static void
Init(void)
{
printf("GL_RENDERER = %s\n", (char*) glGetString(GL_RENDERER));
glLineWidth(3.0);
glPointSize(3.0);
glColor4f(1, 1, 1, 0.8);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
printf("Press 'p' to toggle polygon mode\n");
}
int
main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitWindowPosition(0, 0);
glutInitWindowSize(400, 400);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
Win = glutCreateWindow(argv[0]);
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutDisplayFunc(Draw);
Init();
glutMainLoop();
return 0;
}
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