tests/spec/arb_clip_control/clip-control-depth-precision.c

   1 /*
   2  * Copyright Mathias Fröhlich <Mathias.Froehlich@web.de>
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  21  * DEALINGS IN THE SOFTWARE.
  22  *
  23  * Authors:
  24  *    Mathias Fröhlich <Mathias.Froehlich@web.de>
  25  */
  26
  27 /** @file clip-control-depth-precision.c
  28  *
  29  * Test for ARB_clip_control.
  30  * This is actually the application level use case making use of the
  31  * close to logarithmic depth buffer precision available with the
  32  * GL_ZERO_TO_ONE depth mode that is newly provided with this extension.
  33  * The ARB_clip_control spec gives a set of web references explaining the
  34  * background greatly.
  35  * In short we set up a projection matrix that maps infinite far away
  36  * points to 0 and the near plane to 1. We use a float depth buffer
  37  * with a well known accuracy behavior. That together gives a depth
  38  * buffer resolution that is about the relative floating point accuracy
  39  * relative to the distance from the eye point.
  40  * This extension avoids adding a constant number even in an intermediate
  41  * step which would destroy the effective depth precision possible with
  42  * the floating point depth buffers.
  43  * Roughtly in numbers:
  44  * Two fragments at 5000001 and 5000000 \about 5000001*(1 - eps) distance
  45  * from the eye point should yield to different values in the depth buffer.
  46  * The same goes for about any fragment distance x that you should be able
  47  * to distinguish this from x*(1 - eps).
  48  * And this is exactly what this test checks. We draw two surfaces
  49  * a big red one at a distance x and a half that big green one at a distance
  50  * x*(1 - 10*eps) to have a security factor of 10 to allow for some roundoff
  51  * errors to accumulate. Due to the depth precision we must not get z fighting
  52  * between these two and see a nested green solid square inside a bigger red
  53  * square really behind it.
  54  */
  55
  56 #include "piglit-util-gl.h"
  57
  58 PIGLIT_GL_TEST_CONFIG_BEGIN
  59
  60         config.supports_gl_compat_version = 20;
  61
  62         config.window_visual = PIGLIT_GL_VISUAL_RGB | PIGLIT_GL_VISUAL_DOUBLE;
  63         config.khr_no_error_support = PIGLIT_NO_ERRORS;
  64
  65 PIGLIT_GL_TEST_CONFIG_END
  66
  67 void
  68 piglit_init(int argc, char **argv)
  69 {
  70         GLdouble projection[16] = { 0.0, };
  71
  72         piglit_require_extension("GL_ARB_clip_control");
  73         piglit_require_extension("GL_ARB_depth_buffer_float");
  74         piglit_require_extension("GL_EXT_framebuffer_object");
  75         piglit_require_extension("GL_EXT_framebuffer_blit");
  76
  77         /* Set up a projection matrix mapping z = -1 to z = 1
  78          * and z = -inf to z = 0 in projection space.
  79          * Given the clip control setting below, this is just
  80          * written as is into the float depth buffer.
  81          */
  82         projection[0 + 4*0] = 1;
  83         projection[1 + 4*1] = (GLdouble)piglit_width/piglit_height;
  84         projection[2 + 4*3] = 1;
  85         projection[3 + 4*2] = -1;
  86
  87         glMatrixMode(GL_PROJECTION);
  88         glLoadMatrixd(projection);
  89
  90         glMatrixMode(GL_MODELVIEW);
  91         glLoadIdentity();
  92 }
  93
  94 enum piglit_result
  95 piglit_display(void)
  96 {
  97         GLfloat red[3] = { 1, 0, 0 };
  98         GLfloat green[3] = { 0, 1, 0 };
  99         GLboolean pass = GL_TRUE;
 100         GLuint fb, cb, db;
 101         GLenum status;
 102         int range10;
 103
 104         glGenRenderbuffers(1, &cb);
 105         glBindRenderbuffer(GL_RENDERBUFFER, cb);
 106         glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA, piglit_width, piglit_height);
 107         glBindRenderbuffer(GL_RENDERBUFFER, 0);
 108
 109         glGenRenderbuffers(1, &db);
 110         glBindRenderbuffer(GL_RENDERBUFFER, db);
 111         glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT32F, piglit_width, piglit_height);
 112         glBindRenderbuffer(GL_RENDERBUFFER, 0);
 113
 114         glGenFramebuffers(1, &fb);
 115         glBindFramebuffer(GL_FRAMEBUFFER, fb);
 116         glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, cb);
 117         glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, db);
 118
 119         status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
 120         if (status != GL_FRAMEBUFFER_COMPLETE) {
 121                 printf("FBO incomplete status 0x%X\n", status);
 122                 piglit_report_result(PIGLIT_FAIL);
 123         }
 124
 125         glClipControl(GL_LOWER_LEFT, GL_ZERO_TO_ONE);
 126         glClearDepth(0);
 127         glDepthRange(0, 1);
 128         glClearColor(0, 0, 0, 1);
 129         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 130         glEnable(GL_DEPTH_TEST);
 131         glDepthFunc(GL_GREATER);
 132
 133         for (range10 = 0; range10 < 16; ++range10) {
 134                 int width = piglit_width/4;
 135                 int height = piglit_height/4;
 136                 int tilex = range10 % 4;
 137                 int tiley = range10 / 4;
 138                 int x = tilex*width;
 139                 int y = tiley*height;
 140                 double z = pow(10, 1 + range10);
 141
 142                 /* Set up a new viewport for each depth we want to test */
 143                 glViewport(x, y, width, height);
 144
 145                 /* Draw a red surface at given distance z */
 146                 glColor3fv(red);
 147                 piglit_draw_rect_z(-z, -0.5*z, -0.5*z, z, z);
 148
 149                 pass = piglit_probe_pixel_rgb(x + width/2, y + height/2, red) && pass;
 150
 151                 /* And a green one just close in front of that red one */
 152                 glColor3fv(green);
 153                 piglit_draw_rect_z((10*FLT_EPSILON - 1)*z, -0.25*z, -0.25*z, 0.5*z, 0.5*z);
 154
 155                 pass = piglit_probe_pixel_rgb(x + width/2, y + height/2, green) && pass;
 156         }
 157
 158
 159         /* set viewport to window size */
 160         glViewport(0, 0, piglit_width, piglit_height);
 161
 162         /* copy the result to the back buffer */
 163         glBindFramebuffer(GL_READ_FRAMEBUFFER, fb);
 164         glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
 165         glBlitFramebuffer(0, 0, piglit_width, piglit_height, 0, 0, piglit_width, piglit_height, GL_COLOR_BUFFER_BIT, GL_NEAREST);
 166         glBindFramebuffer(GL_FRAMEBUFFER, 0);
 167
 168         glDeleteFramebuffers(1, &fb);
 169         glDeleteRenderbuffers(1, &cb);
 170         glDeleteRenderbuffers(1, &db);
 171
 172         piglit_present_results();
 173
 174         return pass ? PIGLIT_PASS : PIGLIT_FAIL;
 175 }