progs/tests: new stencilreaddraw.c test

Based on the zreaddraw.c test.

progs/tests/stencilreaddraw.c

@@ -0,0 +1,187 @@
+/*
+ * Test glRead/DrawPixels for GL_STENCIL_INDEX, with pixelzoom.
+ * 
+ * Brian Paul
+ * 8 April 2010
+ */
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <GL/glew.h>
+#include <GL/glut.h>
+
+static GLint WinWidth = 500, WinHeight = 500;
+static GLboolean TestPacking = GL_FALSE;
+static GLboolean TestList = GL_FALSE;
+
+
+static GLuint StencilValue = 192;
+
+static void Display(void)
+{
+   GLubyte stencil[100 * 100 * 2];
+   GLubyte stencil2[400 * 400]; /* *2 to test pixelstore stuff */
+   GLuint list;
+
+   glClearColor(0.5, 0.5, 0.5, 1.0);
+   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
+
+   glEnable(GL_DEPTH_TEST);
+
+   glStencilOp(GL_INVERT, GL_KEEP, GL_REPLACE);
+   glStencilFunc(GL_ALWAYS, StencilValue, ~0);
+   glEnable(GL_STENCIL_TEST);
+
+   /* 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);
+
+   glDisable(GL_STENCIL_TEST);
+
+   if (TestPacking) {
+      glPixelStorei(GL_PACK_ROW_LENGTH, 120);
+      glPixelStorei(GL_PACK_SKIP_PIXELS, 5);
+   }
+
+   /* read the stencil image */
+   glReadPixels(0, 0, 100, 100, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, stencil);
+   {
+      GLubyte min, max;
+      int i;
+      min = max = stencil[0];
+      for (i = 1; i < 100 * 100; i++) {
+         if (stencil[i] < min)
+            min = stencil[i];
+         if (stencil[i] > max)
+            max = stencil[i];
+      }
+      printf("Stencil value range: [%u, %u]\n", min, max);
+      if (max != StencilValue) {
+         printf("Error: expected max stencil val of %u, found %u\n",
+                StencilValue, max);
+      }
+   }
+
+   /* Draw the Z image as luminance above original rendering */
+   glWindowPos2i(0, 100);
+   glDrawPixels(100, 100, GL_LUMINANCE, GL_UNSIGNED_BYTE, stencil);
+
+   if (1) {
+      if (TestPacking) {
+         glPixelStorei(GL_PACK_ROW_LENGTH, 0);
+         glPixelStorei(GL_PACK_SKIP_PIXELS, 0);
+         glPixelStorei(GL_UNPACK_ROW_LENGTH, 120);
+         glPixelStorei(GL_UNPACK_SKIP_PIXELS, 5);
+      }
+
+      /* draw stencil image with scaling (into stencil buffer) */
+      glPixelZoom(4.0, 4.0);
+      glColor4f(1, 0, 0, 0);
+      glWindowPos2i(100, 0);
+
+      if (TestList) {
+         list = glGenLists(1);
+         glNewList(list, GL_COMPILE);
+         glDrawPixels(100, 100, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, stencil);
+         glEndList();
+         glCallList(list);
+         glDeleteLists(list, 1);
+      }
+      else {
+         glDrawPixels(100, 100, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, stencil);
+      }
+
+      if (TestPacking) {
+         glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
+         glPixelStorei(GL_UNPACK_SKIP_PIXELS, 0);
+      }
+
+      /* read back scaled stencil image */
+      glReadPixels(100, 0, 400, 400, GL_STENCIL_INDEX,
+                   GL_UNSIGNED_BYTE, stencil2);
+      /* draw as luminance */
+      glPixelZoom(1.0, 1.0);
+      glWindowPos2i(100, 0);
+      glDrawPixels(400, 400, GL_LUMINANCE, GL_UNSIGNED_BYTE, stencil2);
+   }
+
+   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 'p':
+         TestPacking = !TestPacking;
+         printf("Test pixel pack/unpack: %d\n", TestPacking);
+         break;
+      case 'l':
+         TestList = !TestList;
+         printf("Test dlist: %d\n", TestList);
+         break;
+      case 27:
+         exit(0);
+         break;
+   }
+   glutPostRedisplay();
+}
+
+
+static void Init(void)
+{
+   const GLfloat blue[4] = {.1, .1, 1.0, 1.0};
+   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};
+   GLint bits;
+
+   printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
+   printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
+
+   glGetIntegerv(GL_STENCIL_BITS, &bits);
+   printf("Stencil bits: %d\n", bits);
+
+   assert(bits >= 8);
+
+   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);
+}
+
+
+int main(int argc, char *argv[])
+{
+   glutInit(&argc, argv);
+   glutInitWindowPosition(0, 0);
+   glutInitWindowSize(WinWidth, WinHeight);
+   glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_STENCIL | GLUT_DOUBLE);
+   glutCreateWindow(argv[0]);
+   glewInit();
+   glutReshapeFunc(Reshape);
+   glutKeyboardFunc(Key);
+   glutDisplayFunc(Display);
+   Init();
+   glutMainLoop();
+   return 0;
+}