Test for Freedreno (and Turnip with Zink) occlusion query bug (tested on X1-85)

broken-occlude.c

// gcc broken-occlude.c -o broken-occlude -lGL -lglut
/*
 * Demonstration of Freedreno incorrectly using Early-Z
 * when using occlusion query with alpha-test/discard.
 *
 * The first polygon is drawn with depth write masked,
 * and so Freedreno uses Early-Z, with the reasoning that
 * since the depth buffer is not written to, it's fine to
 * do a depth test even if the fragment is later discarded.
 *
 * The second polygon has depth write enabled, so is not
 * eligible for early Z.
 *
 * The problem is that (it seems that) the occlusion counter
 * update is done in the depth test, so it modifies state even
 * with depth write disabled. So the first polygon gets an
 * incorrect count.
 */

/*
 * Brian Paul
 * 12 June 2003
 *
 * Copyright (C) 2003  Brian Paul   All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * Enhanced by Dave Airlie to add ARB_occlusion_query2
 *
 * Modified to demonstrate a Freedreno bug
 */

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

//#include "glad/gl.h"
//#include "glut_wrap.h"

#define GL_GLEXT_PROTOTYPES
#include <GL/gl.h>
#include <GL/glext.h>
#include <GL/glut.h>

static GLboolean Anim = GL_FALSE;
static GLboolean Printf = GL_TRUE;
static GLfloat Xpos = 0;
static GLuint OccQuery1;
static GLuint OccQuery2;
static GLint Win = 0;

static void
PrintString(const char *s)
{
   if (Printf)
      printf("%s\n", s);
   while (*s) {
      glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
      s++;
   }
}

static void
drawPoly(void)
{
   glAlphaFunc(GL_GEQUAL, 0.5);

   glBegin(GL_POLYGON);

   glColor4f(0, 0, .7, 1);
   glVertex3f(-1, -1, 0);
   glColor4f(.8, 0, 0, .5);
   glVertex3f( 1, -1, 0);
   glColor4f(0, .9, 0, 0);
   glVertex3f( 1,  1, 0);
   glColor4f(0, .4, .4, 1);
   glVertex3f(-1,  1, 0);
   glEnd();
}

static void Idle(void)
{
   static int lastTime = 0;
   static int sign = +1;
   int time = glutGet(GLUT_ELAPSED_TIME);
   float step;

   if (lastTime == 0)
      lastTime = time;
   else if (time - lastTime < 20)  /* 50Hz update */
      return;

   step = (time - lastTime) / 1000.0 * sign;
   lastTime = time;

   Xpos += step;

   if (Xpos > 2.5) {
      Xpos = 2.5;
      sign = -1;
   }
   else if (Xpos < -2.5) {
      Xpos = -2.5;
      sign = +1;
   }
   glutPostRedisplay();
}


static void Display( void )
{
   GLuint passed1;
   GLuint passed2;
   GLint ready;
   char s[100];

   glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

   glMatrixMode( GL_PROJECTION );
   glLoadIdentity();
   glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
   glMatrixMode( GL_MODELVIEW );
   glLoadIdentity();
   glTranslatef( 0.0, 0.0, -15.0 );

   /* draw the occluding polygons */
   /*
   glColor3f(0, 0.6, 0.8);
   glBegin(GL_QUADS);
   glVertex2f(-1.6, -1.5);
   glVertex2f(-0.4, -1.5);
   glVertex2f(-0.4,  1.5);
   glVertex2f(-1.6,  1.5);

   glVertex2f( 0.4, -1.5);
   glVertex2f( 1.6, -1.5);
   glVertex2f( 1.6,  1.5);
   glVertex2f( 0.4,  1.5);
   glEnd();
   */

   /* enable alpha test */
   glEnable(GL_ALPHA_TEST);
   glAlphaFunc(GL_GEQUAL, 0.5);

   /* disable all buffer updates */
   glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
   glDepthMask(GL_TRUE);

   /* draw the first polygon with depth write masked */
   glPushMatrix();
      glTranslatef(Xpos, 0.4, -0.7);
      glScalef(0.3, 0.3, 1.0);
      glRotatef(-90.0 * Xpos, 0, 0, 1);

      glBeginQueryARB(GL_SAMPLES_PASSED_ARB, OccQuery1);

      drawPoly();

      glEndQueryARB(GL_SAMPLES_PASSED_ARB);
   glPopMatrix();

   glDepthMask(GL_FALSE);

   /* draw the second polygon with depth write enabled */
   glPushMatrix();
      glTranslatef(Xpos, -0.4, -0.7);
      glScalef(0.3, 0.3, 1.0);
      glRotatef(-90.0 * Xpos, 0, 0, 1);

      glBeginQueryARB(GL_SAMPLES_PASSED_ARB, OccQuery2);

      drawPoly();

      glEndQueryARB(GL_SAMPLES_PASSED_ARB);
   glPopMatrix();

   /* re-enable buffer updates */
   glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
   glDepthMask(GL_TRUE);

   do {
     /* do useful work here, if any */
     glGetQueryObjectivARB(OccQuery1, GL_QUERY_RESULT_AVAILABLE_ARB, &ready);
   } while (!ready);
   glGetQueryObjectuivARB(OccQuery1, GL_QUERY_RESULT_ARB, &passed1);

   do {
     /* do useful work here, if any */
     glGetQueryObjectivARB(OccQuery2, GL_QUERY_RESULT_AVAILABLE_ARB, &ready);
   } while (!ready);
   glGetQueryObjectuivARB(OccQuery2, GL_QUERY_RESULT_ARB, &passed2);

   glColor3f(0.8, 0.5, 0);

   glPushMatrix();
      glTranslatef(Xpos, 0.4, -0.5);
      glScalef(0.3, 0.3, 1.0);
      glRotatef(-90.0 * Xpos, 0, 0, 1);
      /* draw the first rect, so we can see what's going on */
      drawPoly();
   glPopMatrix();

   glPushMatrix();
      glTranslatef(Xpos, -0.4, -0.5);
      glScalef(0.3, 0.3, 1.0);
      glRotatef(-90.0 * Xpos, 0, 0, 1);
      /* draw the second rect, so we can see what's going on */
      drawPoly();
   glPopMatrix();

   /* Print result message */
   glMatrixMode( GL_PROJECTION );
   glLoadIdentity();
   glOrtho( -1.0, 1.0, -1.0, 1.0, -1.0, 1.0 );
   glMatrixMode( GL_MODELVIEW );
   glLoadIdentity();

   glColor3f(1, 1, 1);

   const char *renderer = (const char *) glGetString(GL_RENDERER);
   glRasterPos3f(-0.9, 0.9, 0);
   PrintString(renderer);

   sprintf(s, " %4d Fragments Visible", passed1);
   glRasterPos3f(-0.50, -0.6, 0);
   PrintString(s);
   if (!passed1) {
      glRasterPos3f(-0.25, -0.7, 0);
      PrintString("Fully Occluded");
   }

   sprintf(s, " %4d Fragments Visible", passed2);
   glRasterPos3f(-0.50, -0.8, 0);
   PrintString(s);
   if (!passed2) {
      glRasterPos3f(-0.25, -0.9, 0);
      PrintString("Fully Occluded");
   }

   if (passed2 > passed1 + 20) {
      glRasterPos3f(-0.44, -0.95, 0);
      PrintString("Freedreno bug detected");
   }

   Printf = GL_FALSE;

   glutSwapBuffers();
}


static void Reshape( int width, int height )
{
   glViewport( 0, 0, width, height );
}


static void Key( unsigned char key, int x, int y )
{
   (void) x;
   (void) y;
   switch (key) {
      case 27:
         glutDestroyWindow(Win);
         exit(0);
         break;
      case ' ':
         Anim = !Anim;
         if (Anim)
            glutIdleFunc(Idle);
         else
            glutIdleFunc(NULL);
         break;
   }
   glutPostRedisplay();
}


static void SpecialKey( int key, int x, int y )
{
   const GLfloat step = 0.1;
   (void) x;
   (void) y;
   switch (key) {
      case GLUT_KEY_LEFT:
         Xpos -= step;
         break;
      case GLUT_KEY_RIGHT:
         Xpos += step;
         break;
   }
   glutPostRedisplay();
}


static void Init( void )
{
   const char *ext = (const char *) glGetString(GL_EXTENSIONS);
   GLint bits;

   if (!strstr(ext, "GL_ARB_occlusion_query")) {
      printf("Sorry, this demo requires the GL_ARB_occlusion_query extension\n");
      exit(-1);
   }

   glGetQueryivARB(GL_SAMPLES_PASSED_ARB, GL_QUERY_COUNTER_BITS_ARB, &bits);

   if (!bits) {
      printf("Hmmm, GL_QUERY_COUNTER_BITS_ARB is zero!\n");
      exit(-1);
   }

   glGenQueriesARB(1, &OccQuery1);
   assert(OccQuery1 > 0);
   glGenQueriesARB(1, &OccQuery2);
   assert(OccQuery2 > 0);

   glEnable(GL_DEPTH_TEST);
}


int main( int argc, char *argv[] )
{
   glutInitWindowSize( 400, 400 );
   glutInit( &argc, argv );
   glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
   Win = glutCreateWindow(argv[0]);
   //gladLoaderLoadGL();
   glutReshapeFunc( Reshape );
   glutKeyboardFunc( Key );
   glutSpecialFunc( SpecialKey );
   glutIdleFunc( NULL );
   glutDisplayFunc( Display );
   Init();
   glutMainLoop();
   //gladLoaderUnloadGL();
   return 0;
}