[Piglit] [PATCH] Add test for ARB_clip_control v3.

Kenneth Graunke kenneth at whitecape.org
Sun Oct 26 21:28:04 PDT 2014


On Sunday, October 26, 2014 03:01:12 AM Ilia Mirkin wrote:
> On Sat, Oct 25, 2014 at 3:45 AM,  <Mathias.Froehlich at gmx.net> wrote:
> > From: Mathias Fröhlich <Mathias.Froehlich at gmx.net>
> >
> > Hi,
> >
> > This adds clip control to the set of piglit tests.
> >
> > please review
> >
> > Mathias
> >
> > v2:
> > Check for ARB_depth_buffer_float where used.
> > Fix and extend comments.
> > Introduce helper for reading and checking the clip control state.
> > Split state and draw related parts into separate methods.
> > Test for Push/PopAttrib.
> >
> > v3:
> > Add tests to tests/all.py.
> >
> > Signed-off-by: Mathias Froehlich <Mathias.Froehlich at web.de>
> > CC: Ilia Mirkin <imirkin at alum.mit.edu>
> > CC: Brian Paul <brianp at vmware.com>
> > ---
> >  registry/gl.xml                                    |  23 +-
> >  tests/all.py                                       |   5 +
> >  tests/spec/CMakeLists.txt                          |   1 +
> >  tests/spec/arb_clip_control/CMakeLists.gl.txt      |  15 ++
> >  tests/spec/arb_clip_control/CMakeLists.txt         |   1 +
> >  .../clip-control-depth-precision.c                 | 186 +++++++++++++++
> >  tests/spec/arb_clip_control/clip-control.c         | 263 
+++++++++++++++++++++
> >  7 files changed, 493 insertions(+), 1 deletion(-)
> >  create mode 100644 tests/spec/arb_clip_control/CMakeLists.gl.txt
> >  create mode 100644 tests/spec/arb_clip_control/CMakeLists.txt
> >  create mode 100644 tests/spec/arb_clip_control/clip-control-depth-
precision.c
> >  create mode 100644 tests/spec/arb_clip_control/clip-control.c
> >
> > diff --git a/registry/gl.xml b/registry/gl.xml
> > index 30e8d9f..d432d3d 100644
> > --- a/registry/gl.xml
> > +++ b/registry/gl.xml
> > @@ -7916,7 +7916,12 @@ typedef unsigned int GLhandleARB;
> >          <enum value="0x934A" name="GL_LOCATION_COMPONENT"/>
> >          <enum value="0x934B" name="GL_TRANSFORM_FEEDBACK_BUFFER_INDEX"/>
> >          <enum value="0x934C" name="GL_TRANSFORM_FEEDBACK_BUFFER_STRIDE"/>
> > -            <unused start="0x934D" end="0x9364"/>
> > +            <unused start="0x934D" end="0x935B"/>
> > +        <enum value="0x935C" name="GL_CLIP_ORIGIN"/>
> > +        <enum value="0x935D" name="GL_CLIP_DEPTH_MODE"/>
> > +        <enum value="0x935E" name="GL_NEGATIVE_ONE_TO_ONE"/>
> > +        <enum value="0x935F" name="GL_ZERO_TO_ONE"/>
> > +            <unused start="0x9360" end="0x9364"/>
> >          <enum value="0x9365" name="GL_CLEAR_TEXTURE"/>
> >              <unused start="0x9366" end="0x937F"/>
> >      </enums>
> > @@ -9085,6 +9090,11 @@ typedef unsigned int GLhandleARB;
> >              <glx type="render" opcode="2"/>
> >          </command>
> >          <command>
> > +            <proto>void <name>glClipControl</name></proto>
> > +            <param><ptype>GLenum</ptype> <name>origin</name></param>
> > +            <param><ptype>GLenum</ptype> <name>depth</name></param>
> > +        </command>
> > +        <command>
> >              <proto><ptype>GLenum</ptype> 
<name>glCheckFramebufferStatus</name></proto>
> >              <param group="FramebufferTarget"><ptype>GLenum</ptype> 
<name>target</name></param>
> >              <glx type="vendor" opcode="1427"/>
> > @@ -33515,6 +33525,17 @@ typedef unsigned int GLhandleARB;
> >                  <command name="glClearTexSubImage"/>
> >              </require>
> >          </extension>
> > +        <extension name="GL_ARB_clip_control" supported="gl">
> > +            <require>
> > +                <enum name="GL_LOWER_LEFT"/>
> > +                <enum name="GL_UPPER_LEFT"/>
> > +                <enum name="GL_NEGATIVE_ONE_TO_ONE"/>
> > +                <enum name="GL_ZERO_TO_ONE"/>
> > +                <enum name="GL_CLIP_ORIGIN"/>
> > +                <enum name="GL_CLIP_DEPTH_MODE"/>
> > +                <command name="glClipControl"/>
> > +            </require>
> > +        </extension>
> >          <extension name="GL_ARB_color_buffer_float" supported="gl">
> >              <require>
> >                  <enum name="GL_RGBA_FLOAT_MODE_ARB"/>
> > diff --git a/tests/all.py b/tests/all.py
> > index ea83695..a629462 100644
> > --- a/tests/all.py
> > +++ b/tests/all.py
> > @@ -2278,6 +2278,11 @@ 
add_fbo_generatemipmap_extension(tdfx_texture_compression_fxt1, 
'GL_3DFX_texture
> >  tdfx_texture_compression_fxt1['invalid formats'] = 
PiglitGLTest('arb_texture_compression-invalid-formats fxt1', 
run_concurrent=True)
> >  add_plain_test(tdfx_texture_compression_fxt1, 'fxt1-teximage')
> >
> > +arb_clip_control = {}
> > +spec['ARB_clip_control'] = arb_clip_control
> > +add_plain_test(arb_clip_control, 'clip-control')
> > +add_plain_test(arb_clip_control, 'clip-control-depth-precision')
> > +
> >  def add_color_buffer_float_test(name, format, p1, p2):
> >      arb_color_buffer_float[format + '-' + name + ('-' + p1 if len(p1) 
else '') + ('-' + p2 if len(p2) else '')] = PiglitGLTest(' 
'.join(['arb_color_buffer_float-' + name, format, p1, p2]), 
run_concurrent=True)
> >
> > diff --git a/tests/spec/CMakeLists.txt b/tests/spec/CMakeLists.txt
> > index b2da115..5a347ae 100644
> > --- a/tests/spec/CMakeLists.txt
> > +++ b/tests/spec/CMakeLists.txt
> > @@ -3,6 +3,7 @@ add_subdirectory (arb_base_instance)
> >  add_subdirectory (arb_buffer_storage)
> >  add_subdirectory (arb_clear_buffer_object)
> >  add_subdirectory (arb_clear_texture)
> > +add_subdirectory (arb_clip_control)
> >  add_subdirectory (arb_color_buffer_float)
> >  add_subdirectory (arb_copy_image)
> >  add_subdirectory (arb_compute_shader)
> > diff --git a/tests/spec/arb_clip_control/CMakeLists.gl.txt 
b/tests/spec/arb_clip_control/CMakeLists.gl.txt
> > new file mode 100644
> > index 0000000..3951bfb
> > --- /dev/null
> > +++ b/tests/spec/arb_clip_control/CMakeLists.gl.txt
> > @@ -0,0 +1,15 @@
> > +include_directories(
> > +       ${GLEXT_INCLUDE_DIR}
> > +       ${OPENGL_INCLUDE_PATH}
> > +)
> > +
> > +link_libraries (
> > +       piglitutil_${piglit_target_api}
> > +       ${OPENGL_gl_LIBRARY}
> > +       ${OPENGL_glu_LIBRARY}
> > +)
> > +
> > +piglit_add_executable (clip-control clip-control.c)
> > +piglit_add_executable (clip-control-depth-precision clip-control-depth-
precision.c)
> > +
> > +# vim: ft=cmake:
> > diff --git a/tests/spec/arb_clip_control/CMakeLists.txt 
b/tests/spec/arb_clip_control/CMakeLists.txt
> > new file mode 100644
> > index 0000000..144a306
> > --- /dev/null
> > +++ b/tests/spec/arb_clip_control/CMakeLists.txt
> > @@ -0,0 +1 @@
> > +piglit_include_target_api()
> > diff --git a/tests/spec/arb_clip_control/clip-control-depth-precision.c 
b/tests/spec/arb_clip_control/clip-control-depth-precision.c
> > new file mode 100644
> > index 0000000..3463ca0
> > --- /dev/null
> > +++ b/tests/spec/arb_clip_control/clip-control-depth-precision.c
> > @@ -0,0 +1,186 @@
> > +/*
> > + * Copyright Mathias Fröhlich <Mathias.Froehlich at web.de>
> > + *
> > + * 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 (including the 
next
> > + * paragraph) 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
> > + * THE AUTHORS OR COPYRIGHT HOLDERS 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.
> > + *
> > + * Authors:
> > + *    Mathias Fröhlich <Mathias.Froehlich at web.de>
> > + */
> > +
> > +/** @file clip-control-depth-precision.c
> > + *
> > + * Test for ARB_clip_control.
> > + * This is actually the application level use case making use of the
> > + * close to logarithmic depth buffer precision available with the
> > + * GL_ZERO_TO_ONE depth mode that is newly provided with this extension.
> > + * The ARB_clip_control spec gives a set of web references explaining the
> > + * background greatly.
> > + * In short we set up a projection matrix that maps infinite far away
> > + * points to 0 and the near plane to 1. We use a float depth buffer
> > + * with a well known accuracy behavior. That together gives a depth
> > + * buffer resolution that is about the relative floating point accuracy
> > + * relative to the distance from the eye point.
> > + * This extension avoids adding a constant number even in an intermediate
> > + * step which would destroy the effective depth precision possible with
> > + * the floating point depth buffers.
> > + * Roughtly in numbers:
> > + * Two fragments at 5000001 and 5000000 \about 5000001*(1 - eps) distance
> > + * from the eye point should yield to different values in the depth 
buffer.
> > + * The same goes for about any fragment distance x that you should be 
able
> > + * to distinguish this from x*(1 - eps).
> > + * And this is exactly what this test checks. We draw two surfaces
> > + * a big red one at a distance x and a half that big green one at a 
distance
> > + * x*(1 - 10*eps) to have a security factor of 10 to allow for some 
roundoff
> > + * errors to accumulate. Due to the depth precision we must not get z 
fighting
> > + * between these two and see a nested green solid square inside a bigger 
red
> > + * square really behind it.
> > + */
> > +
> > +#include "piglit-util-gl.h"
> > +
> > +PIGLIT_GL_TEST_CONFIG_BEGIN
> > +
> > +       config.supports_gl_compat_version = 20;
> > +
> > +       config.window_visual = PIGLIT_GL_VISUAL_RGB | 
PIGLIT_GL_VISUAL_DOUBLE;
> > +
> > +PIGLIT_GL_TEST_CONFIG_END
> > +
> > +void
> > +piglit_init(int argc, char **argv)
> > +{
> > +       GLdouble projection[16] = { 0.0, };
> > +
> > +       piglit_require_extension("GL_ARB_clip_control");
> > +       piglit_require_extension("GL_ARB_depth_buffer_float");
> > +       piglit_require_extension("GL_EXT_framebuffer_object");
> > +       piglit_require_extension("GL_EXT_framebuffer_blit");
> > +
> > +       /* Set up a projection matrix mapping z = -1 to z = 1
> > +        * and z = -inf to z = 0 in projection space.
> > +        * Given the clip control setting below, this is just
> > +        * written as is into the float depth buffer.
> > +        */
> > +       projection[0 + 4*0] = 1;
> > +       projection[1 + 4*1] = (GLdouble)piglit_width/piglit_height;
> > +       projection[2 + 4*3] = 1;
> > +       projection[3 + 4*2] = -1;
> > +
> > +       glMatrixMode(GL_PROJECTION);
> > +       glLoadMatrixd(projection);
> > +
> > +       glMatrixMode(GL_MODELVIEW);
> > +       glLoadIdentity();
> > +}
> > +
> > +void
> > +quad(double px, double py, double pz, double size)
> > +{
> > +       glBegin(GL_QUADS);
> > +       glVertex3d(px - 0.5*size, py - 0.5*size, pz);
> > +       glVertex3d(px + 0.5*size, py - 0.5*size, pz);
> > +       glVertex3d(px + 0.5*size, py + 0.5*size, pz);
> > +       glVertex3d(px - 0.5*size, py + 0.5*size, pz);
> > +       glEnd();
> > +}
> > +
> > +enum piglit_result
> > +piglit_display(void)
> > +{
> > +       GLfloat red[3] = { 1, 0, 0 };
> > +       GLfloat green[3] = { 0, 1, 0 };
> > +       GLboolean pass = GL_TRUE;
> > +       GLuint fb, cb, db;
> > +       GLenum status;
> > +       int range10;
> > +
> > +       glGenRenderbuffers(1, &cb);
> > +       glBindRenderbuffer(GL_RENDERBUFFER, cb);
> > +       glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA, piglit_width, 
piglit_height);
> > +       glBindRenderbuffer(GL_RENDERBUFFER, 0);
> > +
> > +       glGenRenderbuffers(1, &db);
> > +       glBindRenderbuffer(GL_RENDERBUFFER, db);
> > +       glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT32F, 
piglit_width, piglit_height);
> > +       glBindRenderbuffer(GL_RENDERBUFFER, 0);
> > +
> > +       glGenFramebuffers(1, &fb);
> > +       glBindFramebuffer(GL_FRAMEBUFFER, fb);
> > +       glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, 
GL_RENDERBUFFER, cb);
> > +       glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, 
GL_RENDERBUFFER, db);
> > +
> > +       status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
> > +       if (status != GL_FRAMEBUFFER_COMPLETE) {
> > +               printf("FBO incomplete status 0x%X\n", status);
> > +               piglit_report_result(PIGLIT_FAIL);
> > +       }
> > +
> > +       glClipControl(GL_LOWER_LEFT, GL_ZERO_TO_ONE);
> > +       glClearDepth(0);
> > +       glDepthRange(0, 1);
> > +       glClearColor(0, 0, 0, 1);
> > +       glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
> > +       glEnable(GL_DEPTH_TEST);
> > +       glDepthFunc(GL_GREATER);
> > +
> > +       for (range10 = 0; range10 < 16; ++range10) {
> > +               int width = piglit_width/4;
> > +               int height = piglit_height/4;
> > +               int tilex = range10 % 4;
> > +               int tiley = range10 / 4;
> > +               int x = tilex*width;
> > +               int y = tiley*height;
> > +               double z = pow(10, 1 + range10);
> > +
> > +               /* Set up a new viewport for each depth we want to test */
> > +               glViewport(x, y, width, height);
> > +
> > +               /* Draw a red surface at given distance z */
> > +               glColor3fv(red);
> > +               quad(0, 0, -z, z);
> > +
> > +               pass = piglit_probe_pixel_rgb(x + width/2, y + height/2, 
red) && pass;
> > +
> > +               /* And a green one just close in front of that red one */
> > +               glColor3fv(green);
> > +               quad(0, 0, (10*FLT_EPSILON - 1)*z, 0.5*z);
> > +               quad(0, 0, -z, 0.5*z);
> > +
> > +               pass = piglit_probe_pixel_rgb(x + width/2, y + height/2, 
green) && pass;
> > +       }
> > +
> > +
> > +       /* set viewport to window size */
> > +       glViewport(0, 0, piglit_width, piglit_height);
> > +
> > +       /* copy the result to the back buffer */
> > +       glBindFramebuffer(GL_READ_FRAMEBUFFER, fb);
> > +       glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
> > +       glBlitFramebuffer(0, 0, piglit_width, piglit_height, 0, 0, 
piglit_width, piglit_height, GL_COLOR_BUFFER_BIT, GL_NEAREST);
> > +       glBindFramebuffer(GL_FRAMEBUFFER, 0);
> > +
> > +       glDeleteFramebuffers(1, &fb);
> > +       glDeleteRenderbuffers(1, &cb);
> > +       glDeleteRenderbuffers(1, &db);
> > +
> > +       piglit_present_results();
> > +
> > +       return pass ? PIGLIT_PASS : PIGLIT_FAIL;
> > +}
> > diff --git a/tests/spec/arb_clip_control/clip-control.c 
b/tests/spec/arb_clip_control/clip-control.c
> > new file mode 100644
> > index 0000000..b913e40
> > --- /dev/null
> > +++ b/tests/spec/arb_clip_control/clip-control.c
> > @@ -0,0 +1,263 @@
> > +/*
> > + * Copyright Mathias Fröhlich <Mathias.Froehlich at web.de>
> > + *
> > + * 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 (including the 
next
> > + * paragraph) 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
> > + * THE AUTHORS OR COPYRIGHT HOLDERS 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.
> > + *
> > + * Authors:
> > + *    Mathias Fröhlich <Mathias.Froehlich at web.de>
> > + */
> > +
> > +/** @file clip-control.c
> > + *
> > + * Basic test for ARB_clip_contol.
> > + */
> > +
> > +#include "piglit-util-gl.h"
> > +
> > +PIGLIT_GL_TEST_CONFIG_BEGIN
> > +
> > +       config.supports_gl_compat_version = 20;
> > +
> > +       config.window_visual = PIGLIT_GL_VISUAL_RGB | 
PIGLIT_GL_VISUAL_DOUBLE | PIGLIT_GL_VISUAL_DEPTH;
> > +
> > +PIGLIT_GL_TEST_CONFIG_END
> > +
> > +void
> > +piglit_init(int argc, char **argv)
> > +{
> > +       piglit_require_extension("GL_ARB_clip_control");
> > +
> > +       piglit_ortho_projection(piglit_width, piglit_height, GL_FALSE);
> > +}
> > +
> > +void
> > +quad(float base_x, float base_y, float z)
> > +{
> > +       glBegin(GL_QUADS);
> > +       glVertex3f(base_x,      base_y,      z);
> > +       glVertex3f(base_x + 10, base_y,      z);
> > +       glVertex3f(base_x + 10, base_y + 10, z);
> > +       glVertex3f(base_x,      base_y + 10, z);
> > +       glEnd();
> > +}

Why not use piglit_draw_rect_z() for this?

> > +
> > +GLboolean
> > +test_clip_control(GLenum origin, GLenum mode)
> > +{
> > +       GLboolean pass;
> > +       GLint value;
> > +
> > +       pass = piglit_check_gl_error(GL_NO_ERROR);
> > +
> > +       glGetIntegerv(GL_CLIP_ORIGIN, &value);
> > +       if (value != origin) {
> > +               fprintf(stderr, "glClipControl origin unexpected!\n");
> > +               pass = GL_FALSE;
> > +       }
> > +       glGetIntegerv(GL_CLIP_DEPTH_MODE, &value);
> > +       if (value != mode) {
> > +               fprintf(stderr, "glClipControl mode unexpected!\n");
> > +               pass = GL_FALSE;
> > +       }
> > +
> > +       return pass;
> > +}
> > +
> > +GLboolean
> > +state_test(void)
> > +{
> > +       GLboolean pass = GL_TRUE;
> > +
> > +       /* The initial values */
> > +       pass = test_clip_control(GL_LOWER_LEFT, GL_NEGATIVE_ONE_TO_ONE) && 
pass;
> > +
> > +       glClipControl(GL_LOWER_LEFT, GL_ZERO_TO_ONE);
> > +       pass = test_clip_control(GL_LOWER_LEFT, GL_ZERO_TO_ONE) && pass;
> > +
> > +       glClipControl(GL_UPPER_LEFT, GL_ZERO_TO_ONE);
> > +       pass = test_clip_control(GL_UPPER_LEFT, GL_ZERO_TO_ONE) && pass;
> > +
> > +       glClipControl(GL_UPPER_LEFT, GL_NEGATIVE_ONE_TO_ONE);
> > +       pass = test_clip_control(GL_UPPER_LEFT, GL_NEGATIVE_ONE_TO_ONE) && 
pass;
> > +
> > +       /* Check bailing out on invalid input */
> > +       glClipControl(GL_RGB, GL_NEGATIVE_ONE_TO_ONE);
> > +       pass = piglit_check_gl_error(GL_INVALID_ENUM) && pass;
> > +       piglit_reset_gl_error();
> > +       pass = test_clip_control(GL_UPPER_LEFT, GL_NEGATIVE_ONE_TO_ONE) && 
pass;
> > +
> > +       glClipControl(GL_LOWER_LEFT, GL_RGB);
> > +       pass = piglit_check_gl_error(GL_INVALID_ENUM) && pass;
> > +       piglit_reset_gl_error();
> > +       pass = test_clip_control(GL_UPPER_LEFT, GL_NEGATIVE_ONE_TO_ONE) && 
pass;
> > +
> > +
> > +       /* Check push/pop */
> > +       glClipControl(GL_LOWER_LEFT, GL_NEGATIVE_ONE_TO_ONE);
> > +       pass = test_clip_control(GL_LOWER_LEFT, GL_NEGATIVE_ONE_TO_ONE) && 
pass;
> > +
> > +       glPushAttrib(GL_TRANSFORM_BIT);
> > +
> > +       glClipControl(GL_UPPER_LEFT, GL_ZERO_TO_ONE);
> > +       pass = test_clip_control(GL_UPPER_LEFT, GL_ZERO_TO_ONE) && pass;
> > +
> > +       /* Back to default */
> > +       glPopAttrib();
> > +       pass = test_clip_control(GL_LOWER_LEFT, GL_NEGATIVE_ONE_TO_ONE) && 
pass;
> > +
> > +       return pass;
> > +}
> > +
> > +GLboolean
> > +draw_test(void)
> > +{
> > +       GLboolean pass = GL_TRUE;
> > +
> > +       /* Now prepare the draw buffer */
> > +       glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
> > +       glEnable(GL_DEPTH_TEST);
> > +
> > +       /* Also test the winding order logic */
> > +       glEnable(GL_CULL_FACE);
> > +       glCullFace(GL_BACK);
> > +
> > +       /* The clear value - to be sure */
> > +       pass = piglit_probe_pixel_depth(5, 5, 1.0) && pass;
> > +
> > +
> > +
> > +       /* Back to default */
> > +       glClipControl(GL_LOWER_LEFT, GL_NEGATIVE_ONE_TO_ONE);
> > +
> > +       /* inside the clip space */
> > +       quad(10, 10, 1.0);
> > +       quad(10, 30, 0.5);
> > +       quad(10, 50, 0.0);
> > +       quad(10, 70, -0.5);
> > +
> > +       /* outside the clip space */
> > +       quad(10, 90, 1.5);
> > +       quad(10, 110, -1.5);
> > +
> > +       /* the written depth value */
> > +       pass = piglit_probe_pixel_depth(15, 15, 0.0) && pass;
> > +       pass = piglit_probe_pixel_depth(15, 35, 0.25) && pass;
> > +       pass = piglit_probe_pixel_depth(15, 55, 0.5) && pass;
> > +       pass = piglit_probe_pixel_depth(15, 75, 0.75) && pass;
> > +
> > +       /* still the clear value */
> > +       pass = piglit_probe_pixel_depth(15, 95, 1.0) && pass;
> > +       pass = piglit_probe_pixel_depth(15, 115, 1.0) && pass;
> 
> Shouldn't you be clearing in between each one?

It looks like each quad is drawn to a separate location (10/10, 10/30, 10/50, 
10/70 above, 30/10, 30/30, 30/50, 30/70 below), so I'm not sure why you'd need 
to clear.

> > +
> > +
> > +
> > +       glClipControl(GL_LOWER_LEFT, GL_ZERO_TO_ONE);
> > +
> > +       /* inside the clip space */
> > +       quad(30, 10, 0.0);
> > +       quad(30, 30, -0.25);
> > +       quad(30, 50, -0.5);
> > +       quad(30, 70, -0.75);
> 
> Why are these z-values negative? (Same question below as well...)
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