trival: Added test for undefined context of buffer
diff --git a/progs/trivial/clear-undefined.c b/progs/trivial/clear-undefined.c
new file mode 100644
index 0000000..1569860
--- /dev/null
+++ b/progs/trivial/clear-undefined.c
@@ -0,0 +1,130 @@
+/*
+ * glClear + glScissor + Undefined content of framebuffer
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <GL/glut.h>
+
+
+GLenum doubleBuffer;
+GLint Width = 200, Height = 150;
+
+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));
+ fprintf(stderr, "Top right corner should be red\n");
+}
+
+static void Reshape(int width, int height)
+{
+ Width = width;
+ Height = height;
+
+ glViewport(0, 0, (GLint)width, (GLint)height);
+
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
+ glMatrixMode(GL_MODELVIEW);
+}
+
+static void Key(unsigned char key, int x, int y)
+{
+ switch (key) {
+ case 27:
+ exit(1);
+ default:
+ glutPostRedisplay();
+ return;
+ }
+
+}
+
+static void Draw(void)
+{
+ glColor4f(1.0, 0.0, 0.0, 1.0);
+ glBegin(GL_QUADS);
+ glVertex2d(0.0, 0.0);
+ glVertex2d(0.0, 1.0);
+ glVertex2d(1.0, 1.0);
+ glVertex2d(1.0, 0.0);
+ glEnd();
+
+ glEnable(GL_SCISSOR_TEST);
+ glClearColor(1, 1, 0, 0);
+ glScissor(Width / 2, 0, Width - Width / 2, Height / 2);
+ glClear(GL_COLOR_BUFFER_BIT);
+
+ glClearColor(0, 0, 1, 0);
+ glScissor(0, Height / 2, Width / 2, Height - Height / 2);
+ glClear(GL_COLOR_BUFFER_BIT);
+ glDisable(GL_SCISSOR_TEST);
+
+ glColor4f(0.0, 1.0, 0.0, 1.0);
+ glBegin(GL_QUADS);
+ glVertex2d( 0.0, 0.0);
+ glVertex2d( 0.0, -1.0);
+ glVertex2d(-1.0, -1.0);
+ glVertex2d(-1.0, 0.0);
+ glEnd();
+
+ glFlush();
+
+ if (doubleBuffer) {
+ glutSwapBuffers();
+ }
+}
+
+static GLenum Args(int argc, char **argv)
+{
+ GLint i;
+
+ doubleBuffer = GL_TRUE;
+
+ for (i = 1; i < argc; i++) {
+ if (strcmp(argv[i], "-sb") == 0) {
+ doubleBuffer = GL_FALSE;
+ } else if (strcmp(argv[i], "-db") == 0) {
+ doubleBuffer = GL_TRUE;
+ } else {
+ fprintf(stderr, "%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( Width, Height );
+
+
+ type = GLUT_RGB | GLUT_ALPHA;
+ type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
+ glutInitDisplayMode(type);
+
+ if (glutCreateWindow(argv[0]) == GL_FALSE) {
+ exit(1);
+ }
+
+ Init();
+ Reshape(Width, Height);
+
+ glutReshapeFunc(Reshape);
+ glutKeyboardFunc(Key);
+ glutDisplayFunc(Draw);
+ glutMainLoop();
+ return 0;
+}