diff options
Diffstat (limited to 'progs/trivial/tri-stencil.c')
| -rw-r--r-- | progs/trivial/tri-stencil.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/progs/trivial/tri-stencil.c b/progs/trivial/tri-stencil.c index 9f68bca914..d66b68c415 100644 --- a/progs/trivial/tri-stencil.c +++ b/progs/trivial/tri-stencil.c @@ -77,6 +77,7 @@ static void Draw(void) glStencilFunc(GL_ALWAYS, 1, 1); glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE); + /* red triangle (setting stencil to 1) */ glColor3ub(200, 0, 0); glBegin(GL_POLYGON); glVertex3i(-4, -4, 0); @@ -88,6 +89,7 @@ static void Draw(void) glStencilFunc(GL_EQUAL, 1, 1); glStencilOp(GL_INCR, GL_KEEP, GL_DECR); + /* green quad (if over red, decr stencil to 0, else incr to 1) */ glColor3ub(0, 200, 0); glBegin(GL_POLYGON); glVertex3i(3, 3, 0); @@ -101,6 +103,7 @@ static void Draw(void) glStencilFunc(GL_EQUAL, 1, 1); glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP); + /* blue quad (where stencil == 1) */ glColor3ub(0, 0, 200); glBegin(GL_POLYGON); glVertex3f(2.5, 2.5, 0); |