tests/shaders/glsl-fs-fragcoord-zw-perspective.c

   1 /*
   2  * Copyright © 2009 Intel Corporation
   3  * Copyright © 2011 VMware, Inc.
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   9  * and/or sell copies of the Software, and to permit persons to whom the
  10  * Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice (including the next
  13  * paragraph) shall be included in all copies or substantial portions of the
  14  * Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  22  * IN THE SOFTWARE.
  23  *
  24  * Authors:
  25  *    Eric Anholt <eric@anholt.net>
  26  *    Brian Paul
  27  *
  28  */
  29
  30 /** @file glsl-fs-fragcoord-zw-perspective.c
  31  *
  32  * Tests that gl_FragCoord.zw produces the expected output in a fragment shader
  33  * with a perspective projection.
  34  */
  35
  36 #include "piglit-util-gl.h"
  37
  38 PIGLIT_GL_TEST_CONFIG_BEGIN
  39
  40         config.supports_gl_compat_version = 10;
  41
  42         config.window_width = 256;
  43         config.window_height = 256;
  44         config.window_visual = PIGLIT_GL_VISUAL_RGB | PIGLIT_GL_VISUAL_DOUBLE | PIGLIT_GL_VISUAL_DEPTH;
  45         config.khr_no_error_support = PIGLIT_NO_ERRORS;
  46
  47 PIGLIT_GL_TEST_CONFIG_END
  48
  49 static GLfloat Znear = 1.0, Zfar = 10.0;
  50
  51
  52 /**
  53  * Draw a quad where the bottom edge is on the near clip plane and the
  54  * top edge is on the far clip plane.  Adjust the far coordinates' X and Y
  55  * values to fill the window.  So the quad doesn't look like it's drawn in
  56  * perspective, but it is (the top is much wider than the bottom).
  57  */
  58 static void
  59 draw_quad(void)
  60 {
  61         float xBotLeft = -Znear, xBotRight = Znear;
  62         float xTopLeft = -Zfar, xTopRight = Zfar;
  63         float yBotLeft = -Znear, yBotRight = -Znear;
  64         float yTopLeft = Zfar, yTopRight = Zfar;
  65         float zBottom = -Znear, zTop = -Zfar;
  66         float verts[4][4];
  67
  68         verts[0][0] = xBotLeft;
  69         verts[0][1] = yBotLeft;
  70         verts[0][2] = zBottom;
  71         verts[0][3] = 1.0;
  72         verts[1][0] = xBotRight;
  73         verts[1][1] = yBotRight;
  74         verts[1][2] = zBottom;
  75         verts[1][3] = 1.0;
  76         verts[2][0] = xTopRight;
  77         verts[2][1] = yTopRight;
  78         verts[2][2] = zTop;
  79         verts[2][3] = 1.0;
  80         verts[3][0] = xTopLeft;
  81         verts[3][1] = yTopLeft;
  82         verts[3][2] = zTop;
  83         verts[3][3] = 1.0;
  84
  85         glVertexPointer(4, GL_FLOAT, 0, verts);
  86         glEnableClientState(GL_VERTEX_ARRAY);
  87
  88         glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
  89
  90         glDisableClientState(GL_VERTEX_ARRAY);
  91 }
  92
  93
  94 /** Convert t in [0,1] into a 1/w value */
  95 static float
  96 t_to_w(float t)
  97 {
  98         float zEye = -(Znear + t * (Zfar - Znear));
  99         float wClip = -zEye;
 100         return 1.0 / wClip;
 101 }
 102
 103
 104 enum piglit_result
 105 piglit_display(void)
 106 {
 107         float w0, w1;
 108         GLboolean pass = GL_TRUE;
 109         int y;
 110
 111         glClearColor(0.5, 0.5, 0.5, 0.5);
 112         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 113
 114         draw_quad();
 115
 116         /* Spot-test Z values */
 117         pass = piglit_probe_pixel_depth(0, 0, 0.0) && pass;
 118         pass = piglit_probe_pixel_depth(piglit_width-1, 0, 0.0) && pass;
 119         pass = piglit_probe_pixel_depth(piglit_width-2, piglit_height-1, 1.0) && pass;
 120         pass = piglit_probe_pixel_depth(1, piglit_height-2, 1.0) && pass;
 121
 122         w0 = t_to_w(0.0);
 123         w1 = t_to_w(1.0);
 124
 125         /* Test a column of pixel colors */
 126         for (y = 8; y < piglit_height; y += 16) {
 127                 float expected[3];
 128                 float t = y / (float) (piglit_height - 1);
 129                 expected[0] = t;                   /* gl_FragCoord.z */
 130                 expected[1] = w0 + t * (w1 - w0);  /* gl_FragCoord.w */
 131                 expected[2] = 0.0;
 132
 133                 pass = piglit_probe_pixel_rgb(piglit_width/2, y, expected) & pass;
 134         }
 135
 136         piglit_present_results();
 137
 138         return pass ? PIGLIT_PASS : PIGLIT_FAIL;
 139 }
 140
 141 void
 142 piglit_init(int argc, char **argv)
 143 {
 144         GLint vs, fs, prog;
 145
 146         piglit_require_gl_version(20);
 147
 148         glMatrixMode(GL_PROJECTION);
 149         glLoadIdentity();
 150         glFrustum(-1.0, 1.0, -1.0, 1.0, Znear, Zfar);
 151         glMatrixMode(GL_MODELVIEW);
 152         glLoadIdentity();
 153
 154         vs = piglit_compile_shader(GL_VERTEX_SHADER,
 155                                    "shaders/glsl-mvp.vert");
 156         fs = piglit_compile_shader(GL_FRAGMENT_SHADER,
 157                                    "shaders/glsl-fs-fragcoord-zw.frag");
 158
 159         prog = piglit_link_simple_program(vs, fs);
 160
 161         glUseProgram(prog);
 162
 163         glEnable(GL_DEPTH_TEST);
 164 }