[Piglit] [PATCH 16/17 v2] fbo-depth-sample-compare: Eliminate dependency on gluSphere
Ian Romanick
idr at freedesktop.org
Tue Sep 22 10:10:25 PDT 2015
From: Ian Romanick <ian.d.romanick at intel.com>
v2: Fix typo in comment noticed by Matt. When interpolating from the
north pole to the south pole of the sphere, correctly interpolate from 0
to pi instead of 0 to 2pi. See the "NOTE" in the code.
Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Acked-by: Matt Turner <mattst88 at gmail.com>
---
tests/fbo/CMakeLists.gl.txt | 1 -
tests/fbo/fbo-depth-sample-compare.c | 145 +++++++++++++++++++++++++++++++----
2 files changed, 129 insertions(+), 17 deletions(-)
diff --git a/tests/fbo/CMakeLists.gl.txt b/tests/fbo/CMakeLists.gl.txt
index d5c8778..0476b10 100644
--- a/tests/fbo/CMakeLists.gl.txt
+++ b/tests/fbo/CMakeLists.gl.txt
@@ -8,7 +8,6 @@ include_directories(
link_libraries (
piglitutil_${piglit_target_api}
${OPENGL_gl_LIBRARY}
- ${OPENGL_glu_LIBRARY}
)
piglit_add_executable (fbo-1d fbo-1d.c)
diff --git a/tests/fbo/fbo-depth-sample-compare.c b/tests/fbo/fbo-depth-sample-compare.c
index 7d78913..8136f40 100644
--- a/tests/fbo/fbo-depth-sample-compare.c
+++ b/tests/fbo/fbo-depth-sample-compare.c
@@ -1,5 +1,6 @@
/*
* Copyright (c) 2011 VMware, Inc.
+ * Copyright © 2015 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
@@ -39,13 +40,6 @@
#include <assert.h>
#include "piglit-util-gl.h"
-#if defined(__APPLE__)
-# include <OpenGL/glu.h>
-#else
-# include <GL/glu.h>
-#endif
-
-
/** Set DEBUG to 1 to enable extra output when trying to debug failures */
#define DEBUG 0
@@ -66,7 +60,6 @@ static GLuint ColorTex, DepthTex, FBO;
static GLuint ShaderProg;
static GLint Zbits;
static GLenum TexTarget = GL_TEXTURE_2D;
-static GLUquadricObj *sphereObj = NULL;
static void
@@ -237,13 +230,135 @@ find_uint_min_max_center(const GLuint *buf, GLuint n,
static void
draw_sphere(void)
{
- GLdouble radius = 0.95;
- GLint slices = 40;
- GLint stacks = 20;
+ /* Without this enum hack, GCC complains about variable length arrays
+ * below... even if you make the variables const.
+ */
+ enum {
+ slices = 40,
+ stacks = 20,
+
+ /* There are (stacks - 1) interior stacks (see the comment before y
+ * below). Each interior stack is (slices + 1) vertices. There is on
+ * additional vertex at the top, and there is one at the bottom.
+ */
+ num_vertices = (stacks - 1) * (slices + 1) + 2,
+
+ /* Each slice is a single triangle strip. There is a triangle at the
+ * top (3 elements), and there is one at the bottom (1 element).
+ * Between is (stacks - 2) quadrilaterals (2 elements each).
+ */
+ elements_per_slice = 3 + ((stacks - 2) * 2) + 1,
+ };
+
+ const GLdouble radius = 0.95;
+ unsigned i;
+
+ static float vertex_data[num_vertices * 4];
+ static unsigned element_data[elements_per_slice * slices];
+ static bool generated = false;
+
+ if (!generated) {
+ float *v = vertex_data;
+ unsigned *e = element_data;
+ unsigned j;
+
+ assert(num_vertices < 65535);
+
+ for (i = 1; i < stacks; i++) {
+ /* The y values of the sphere interpolate from -radius to radius.
+ * The two extrema have a single point (in terms of the "circular
+ * slice" mentioned below, r_c = 0). Those points are generated at
+ * the very end. If there are N slices of the sphere, there are N+1
+ * layers of data. This loop generates data for layers 1 through
+ * N-1, inclusive. Layers 0 and N are the extrema previously
+ * mentioned.
+ *
+ * NOTE: Then angle range from the north pole to the south pole is
+ * PI. When going around the equator (inner loop below), the angle
+ * range is 0 to 2PI.
+ */
+ const double y = -cos(i * M_PI / stacks) * radius;
+
+ /* The radius of the sphere is, r_s, sqrt(x**2 + y**2 + z**2). The
+ * radius of the circular slice of the sphere parallel to the X/Z
+ * plane, r_c, is sqrt(x**2 + z**2). r_s and y are known. Solve for
+ * r_c.
+ *
+ * r_s**2 = x**2 + y**2 + z**2
+ * r_s**2 = r_c**2 + y**2
+ * r_c**2 = r_s**2 - y**2
+ * r_c = sqrt(r_s**2 - y**2)
+ */
+ const double r_c = sqrt((radius * radius) - (y * y));
+
+ for (j = 0; j <= slices; j++) {
+ const double angle = j * 2.0 * M_PI / slices;
+
+ v[0] = r_c * sin(angle);
+ v[1] = y;
+ v[2] = r_c * cos(angle);
+ v[3] = 1.0;
+
+ assert(fabs(v[0] * v[0] + v[1] * v[1] + v[2] * v[2] -
+ radius * radius) < 1e-6);
+ v += 4;
+ assert(v < &vertex_data[ARRAY_SIZE(vertex_data)]);
+ }
+ }
+
+ v[0] = 0.0;
+ v[1] = -radius;
+ v[2] = 0.0;
+ v[3] = 1.0;
+
+ v[4] = 0.0;
+ v[5] = radius;
+ v[6] = 0.0;
+ v[7] = 1.0;
+ assert(&v[8] == &vertex_data[ARRAY_SIZE(vertex_data)]);
+
+ for (i = 0; i < slices; i++) {
+ /* The outer loop walks around the first circluar slice of vertex
+ * data. This occupies vertices [0, slices]. Looking at the sphere,
+ * there is a vertex on the left side of the polygon being emitted,
+ * and the next vertex in the sequence is on the right.
+ */
+ unsigned left = i;
+
+ /* Emit the "base" triangle. */
+ e[0] = num_vertices - 2;
+ e++;
+ assert(e < &element_data[ARRAY_SIZE(element_data)]);
+
+ for (j = 0; j < (stacks - 1); j++) {
+ const unsigned right = left + 1;
+
+ e[0] = left;
+ e[1] = right;
+ e += 2;
+ assert(e < &element_data[ARRAY_SIZE(element_data)]);
+
+ left += (slices + 1);
+ }
+
+ /* Emit the bottom vertex for the final triangle. */
+ e[0] = num_vertices - 1;
+ e++;
+ assert(e <= &element_data[ARRAY_SIZE(element_data)]);
+ }
- gluQuadricDrawStyle(sphereObj, GLU_FILL);
- gluQuadricNormals(sphereObj, GLU_SMOOTH);
- gluSphere(sphereObj, radius, slices, stacks);
+ assert(e == &element_data[ARRAY_SIZE(element_data)]);
+ generated = true;
+ }
+
+ glVertexPointer(4, GL_FLOAT, 4 * sizeof(float), vertex_data);
+ glEnableClientState(GL_VERTEX_ARRAY);
+ for (i = 0; i < slices; i++) {
+ glDrawElements(GL_TRIANGLE_STRIP,
+ elements_per_slice,
+ GL_UNSIGNED_INT,
+ &element_data[i * elements_per_slice]);
+ }
}
@@ -528,8 +643,6 @@ piglit_init(int argc, char **argv)
create_frag_shader();
- sphereObj = gluNewQuadric();
-
if (!piglit_automatic) {
printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
printf("Left: Shader showing difference pixels (black=good, red=error)\n");
--
2.1.0
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