#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <GL/glut.h>
static void Init(void)
{
glShadeModel(GL_FLAT);
glClearColor(0.0, 0.0, 0.0, 0.0);
glClearStencil(0);
glStencilMask(1);
glEnable(GL_STENCIL_TEST);
}
static void Reshape(int width, int height)
{
glViewport(0, 0, (GLint)width, (GLint)height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-5.0, 5.0, -5.0, 5.0, -5.0, 5.0);
glMatrixMode(GL_MODELVIEW);
}
static void Key(unsigned char key, int x, int y)
{
switch (key) {
case 27:
exit(1);
}
}
static void Draw(void)
{
glClear(GL_COLOR_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);
glStencilFunc(GL_ALWAYS, 1, 1);
glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
glColor3ub(200, 0, 0);
glBegin(GL_POLYGON);
glVertex3i(-4, -4, 0);
glVertex3i( 4, -4, 0);
glVertex3i( 0, 4, 0);
glEnd();
glStencilFunc(GL_EQUAL, 1, 1);
glStencilOp(GL_INCR, GL_KEEP, GL_DECR);
glColor3ub(0, 200, 0);
glBegin(GL_POLYGON);
glVertex3i(3, 3, 0);
glVertex3i(-3, 3, 0);
glVertex3i(-3, -3, 0);
glVertex3i(3, -3, 0);
glEnd();
glStencilFunc(GL_EQUAL, 1, 1);
glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
glColor3ub(0, 0, 200);
glBegin(GL_POLYGON);
glVertex3i(3, 3, 0);
glVertex3i(-3, 3, 0);
glVertex3i(-3, -3, 0);
glVertex3i(3, -3, 0);
glEnd();
glFlush();
}
static GLenum Args(int argc, char **argv)
{
GLint i;
for (i = 1; i < argc; i++) {
if (strcmp(argv[i], "-dr") == 0) {
} else {
printf("%s (Bad option).\n", argv[i]);
return GL_FALSE;
}
}
return GL_TRUE;
}
int main(int argc, char **argv)
{
GLenum type;
glutInit(&argc, argv);
if (Args(argc, argv) == GL_FALSE) {
exit(1);
}
glutInitWindowPosition(0, 0); glutInitWindowSize( 300, 300);
type = GLUT_RGB | GLUT_SINGLE | GLUT_STENCIL;
glutInitDisplayMode(type);
if (glutCreateWindow("Stencil Test") == GL_FALSE) {
exit(1);
}
Init();
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutDisplayFunc(Draw);
glutMainLoop();
return 0;
}