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Diffstat (limited to 'progs/trivial/tri-cull.c')
-rw-r--r--progs/trivial/tri-cull.c86
1 files changed, 61 insertions, 25 deletions
diff --git a/progs/trivial/tri-cull.c b/progs/trivial/tri-cull.c
index 20aeaf1d7c..2eead84115 100644
--- a/progs/trivial/tri-cull.c
+++ b/progs/trivial/tri-cull.c
@@ -27,25 +27,45 @@
#include <stdlib.h>
#include <GL/glut.h>
+static GLenum doubleBuffer;
+static GLint cullmode = 0;
+static GLenum front = GL_CCW; /* GL default */
-#define CI_OFFSET_1 16
-#define CI_OFFSET_2 32
-
-
-GLenum doubleBuffer;
+static void cull(void)
+{
+ cullmode = (cullmode + 1) % 4;
+ if (cullmode == 0) {
+ glCullFace(GL_FRONT);
+ glEnable(GL_CULL_FACE);
+ printf("cull GL_FRONT\n");
+ }
+ else if (cullmode == 1) {
+ glCullFace(GL_BACK);
+ glEnable(GL_CULL_FACE);
+ printf("cull GL_BACK\n");
+ }
+ else if (cullmode == 2) {
+ glCullFace(GL_FRONT_AND_BACK);
+ glEnable(GL_CULL_FACE);
+ printf("cull GL_FRONT_AND_BACK\n");
+ }
+ else {
+ glDisable(GL_CULL_FACE);
+ printf("cull none\n");
+ }
+}
static void Init(void)
{
fprintf(stderr, "GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
fprintf(stderr, "GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
fprintf(stderr, "GL_VENDOR = %s\n", (char *) glGetString(GL_VENDOR));
-
- glClearColor(0.0, 0.0, 1.0, 0.0);
+ glClearColor(0.0, 0.0, 1.0, 0.0);
+ cull();
}
static void Reshape(int width, int height)
{
-
glViewport(0, 0, (GLint)width, (GLint)height);
glMatrixMode(GL_PROJECTION);
@@ -56,15 +76,21 @@ static void Reshape(int width, int height)
static void Key(unsigned char key, int x, int y)
{
-
- switch (key) {
- case 27:
- exit(1);
- default:
- return;
- }
-
- glutPostRedisplay();
+ switch (key) {
+ case 27:
+ exit(1);
+ case 'c':
+ cull();
+ break;
+ case 'f':
+ front = ((front == GL_CCW) ? GL_CW : GL_CCW);
+ glFrontFace(front);
+ printf("front face = %s\n", front == GL_CCW ? "GL_CCW" : "GL_CW");
+ break;
+ default:
+ return;
+ }
+ glutPostRedisplay();
}
static void Draw(void)
@@ -72,12 +98,22 @@ static void Draw(void)
glClear(GL_COLOR_BUFFER_BIT);
glBegin(GL_TRIANGLES);
- glColor3f(0,0,1);
- glVertex3f( -1.5, 0.5, -30.0);
- glColor3f(1,0,0);
- glVertex3f( 0, 2.0, -30.0);
- glColor3f(0,1,0);
- glVertex3f(-1.5, 2.0, -30.0);
+ /* CCW / front-facing */
+ glColor3f(0,0,.7);
+ glVertex3f(-0.1, -0.9, -30.0);
+ glColor3f(.8,0,0);
+ glVertex3f(-0.1, 0.9, -30.0);
+ glColor3f(0,.9,0);
+ glVertex3f(-0.9, 0.0, -30.0);
+
+ /* CW / back-facing */
+ glColor3f(0,0,.7);
+ glVertex3f( 0.1, -0.9, -30.0);
+ glColor3f(.8,0,0);
+ glVertex3f( 0.1, 0.9, -30.0);
+ glColor3f(0,.9,0);
+ glVertex3f( 0.9, 0.0, -30.0);
+
glEnd();
glFlush();
@@ -118,7 +154,7 @@ int main(int argc, char **argv)
glutInitWindowPosition(0, 0); glutInitWindowSize( 250, 250);
- type = GLUT_RGB;
+ type = GLUT_RGB | GLUT_ALPHA;
type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
glutInitDisplayMode(type);
@@ -132,5 +168,5 @@ int main(int argc, char **argv)
glutKeyboardFunc(Key);
glutDisplayFunc(Draw);
glutMainLoop();
- return 0;
+ return 0;
}