test program to exercise glDraw/ReadPixels(GL_DEPTH_COMPONENT) and pixel zooming

diff --git a/progs/tests/zreaddraw.c b/progs/tests/zreaddraw.c
new file mode 100644 (file)
index 0000000..e2dacbf
--- /dev/null
+++ b/progs/tests/zreaddraw.c
@@ -0,0 +1,116 @@
+/*
+ * Test glRead/DrawPixels for GL_DEPTH_COMPONENT, with pixelzoom.
+ * 
+ * Brian Paul
+ * 23 August 2003
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#define GL_GLEXT_PROTOTYPES
+#include <GL/glut.h>
+
+static GLint WinWidth = 500, WinHeight = 500;
+
+
+static void Display(void)
+{
+   GLfloat depth[100 * 100];
+   GLfloat depth2[400 * 400];
+   GLfloat min, max;
+   int i;
+
+   glClearColor(0.5, 0.5, 0.5, 0);
+   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+   /* draw a sphere */
+   glViewport(0, 0, 100, 100);
+   glMatrixMode(GL_PROJECTION);
+   glLoadIdentity();
+   glOrtho(-1, 1, -1, 1, -1, 0);  /* clip away back half of sphere */
+   glMatrixMode(GL_MODELVIEW);
+   glLoadIdentity();
+   glutSolidSphere(1.0, 20, 10);
+
+   /* read the depth image */
+   glReadPixels(0, 0, 100, 100, GL_DEPTH_COMPONENT, GL_FLOAT, depth);
+   min = max = depth[0];
+   for (i = 1; i < 100 * 100; i++) {
+      if (depth[i] < min)
+         min = depth[i];
+      if (depth[i] > max)
+         max = depth[i];
+   }
+   printf("Depth value range: [%f, %f]\n", min, max);
+
+   /* draw depth image with scaling (into z buffer) */
+   glPixelZoom(4.0, 4.0);
+   glWindowPos2i(100, 0);
+   glDrawPixels(100, 100, GL_DEPTH_COMPONENT, GL_FLOAT, depth);
+
+   /* read back scaled depth image */
+   glReadPixels(100, 0, 400, 400, GL_DEPTH_COMPONENT, GL_FLOAT, depth2);
+   /* draw as luminance */
+   glPixelZoom(1.0, 1.0);
+   glDrawPixels(400, 400, GL_LUMINANCE, GL_FLOAT, depth2);
+
+   glutSwapBuffers();
+}
+
+
+static void Reshape(int width, int height)
+{
+   WinWidth = width;
+   WinHeight = height;
+   glViewport(0, 0, width, height);
+}
+
+
+static void Key(unsigned char key, int x, int y)
+{
+   (void) x;
+   (void) y;
+   switch (key) {
+      case 27:
+         exit(0);
+         break;
+   }
+   glutPostRedisplay();
+}
+
+
+static void Init(void)
+{
+   const GLfloat blue[4] = {.1, .1, 1.0, 0.0};
+   const GLfloat gray[4] = {0.2, 0.2, 0.2, 1.0};
+   const GLfloat white[4] = {1.0, 1.0, 1.0, 1.0};
+   const GLfloat pos[4] = {0, 0, 10, 0};
+
+   printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
+   printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
+
+   glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, blue);
+   glLightfv(GL_LIGHT0, GL_AMBIENT, gray);
+   glLightfv(GL_LIGHT0, GL_DIFFUSE, white);
+   glLightfv(GL_LIGHT0, GL_POSITION, pos);
+   glEnable(GL_LIGHTING);
+   glEnable(GL_LIGHT0);
+   glEnable(GL_DEPTH_TEST);
+}
+
+
+int main(int argc, char *argv[])
+{
+   glutInit(&argc, argv);
+   glutInitWindowPosition(0, 0);
+   glutInitWindowSize(WinWidth, WinHeight);
+   glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
+   glutCreateWindow(argv[0]);
+   glutReshapeFunc(Reshape);
+   glutKeyboardFunc(Key);
+   glutDisplayFunc(Display);
+   Init();
+   glutMainLoop();
+   return 0;
+}