Demos (master): trivial/tri-rotate: draw a triangle with rotation

[Brian Paul]

Module: Demos
Branch: master
Commit: 613e19b8cd2094bd05cb7480de9e13edd54de18c
URL:    http://cgit.freedesktop.org/mesa/demos/commit/?id=613e19b8cd2094bd05cb7480de9e13edd54de18c

Author: Brian Paul <brianp at vmware.com>
Date:   Wed Jul 24 11:28:24 2013 -0600

trivial/tri-rotate: draw a triangle with rotation

Specify initial rotation on command line.  Press r/R to rotate
interactively.

---

 src/trivial/CMakeLists.txt |    1 +
 src/trivial/Makefile.am    |    1 +
 src/trivial/tri-rotate.c   |  107 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 109 insertions(+), 0 deletions(-)

diff --git a/src/trivial/CMakeLists.txt b/src/trivial/CMakeLists.txt
index ed6445b..b42d1f9 100644
--- a/src/trivial/CMakeLists.txt
+++ b/src/trivial/CMakeLists.txt
@@ -147,6 +147,7 @@ set (targets
 	tri-point-line-clipped
 	tri-query
 	tri-repeat
+	tri-rotate
 	tri-scissor-tri
 	tri-square
 	tri-stencil
diff --git a/src/trivial/Makefile.am b/src/trivial/Makefile.am
index 2543068..87d4e40 100644
--- a/src/trivial/Makefile.am
+++ b/src/trivial/Makefile.am
@@ -159,6 +159,7 @@ bin_PROGRAMS = \
 	tri-point-line-clipped \
 	tri-query \
 	tri-repeat \
+	tri-rotate \
 	tri-scissor-tri \
 	tri-square \
 	tri-stencil \
diff --git a/src/trivial/tri-rotate.c b/src/trivial/tri-rotate.c
new file mode 100644
index 0000000..357de59
--- /dev/null
+++ b/src/trivial/tri-rotate.c
@@ -0,0 +1,107 @@
+/*
+ * Draw a triangle with rotation
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "glut_wrap.h"
+
+
+static int win;
+static float rot = 0.0f;
+
+
+static void
+Reshape(int width, int height)
+{
+   glViewport(0, 0, width, height);
+
+   glMatrixMode(GL_PROJECTION);
+   glLoadIdentity();
+   glMatrixMode(GL_MODELVIEW);
+   glLoadIdentity();
+}
+
+
+static void
+Key(unsigned char key, int x, int y)
+{
+   if (key == 27) {
+      glutDestroyWindow(win);
+      exit(0);
+   }
+   else if (key == 'r') {
+      rot += 5.0f;
+      glutPostRedisplay();
+   }
+   else if (key == 'R') {
+      rot -= 5.0f;
+      glutPostRedisplay();
+   }
+}
+
+
+static void
+Draw(void)
+{
+   glClear(GL_COLOR_BUFFER_BIT); 
+
+   glPushMatrix();
+   glRotatef(rot, 0.0, 0.0, 1.0f);
+
+   glBegin(GL_TRIANGLES);
+   glColor3f(1.0f, 0.0f, 0.0f); 
+   glVertex3f(-0.8f, -0.8f, 0.0f);
+   glColor3f(0.0f, 1.0f, 0.0f); 
+   glVertex3f(0.8f, -0.8f, 0.0f);
+   glColor3f(0.0f, 0.0f, 1.0f); 
+   glVertex3f(0.0f, 0.8f, 0.0f);
+   glEnd();
+
+   glPopMatrix();
+
+   glutSwapBuffers();
+}
+
+
+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));
+   fflush(stderr);
+
+   glClearColor(0.3, 0.3, 0.7, 0.0);
+}
+
+
+int
+main(int argc, char **argv)
+{
+   glutInit(&argc, argv);
+
+   if (argc > 1) {
+      rot = atof(argv[1]);
+      printf("Using rotation %g\n", rot);
+      fflush(stdout);
+   }
+
+   glutInitWindowPosition(0, 0);
+   glutInitWindowSize(250, 250);
+
+   glutInitDisplayMode(GLUT_RGB | GLUT_ALPHA | GLUT_DOUBLE);
+
+   win = glutCreateWindow(*argv);
+   if (!win) {
+      exit(1);
+   }
+
+   Init();
+
+   glutReshapeFunc(Reshape);
+   glutKeyboardFunc(Key);
+   glutDisplayFunc(Draw);
+   glutMainLoop();
+   return 0;
+}