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/*
* Copyright © 2011 Intel Corporation
*
* 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.
*/
/**
* \file order.c
*
* Confirm that the order of vertices output by transform feedback
* matches the order of vertices supplied to the GL pipeline.
*
* On OpenGL implementations that execute multiple vertex shader
* threads in parallel, it's possible that the threads won't complete
* in the same order that they were invoked. When this happens, it's
* critical that transform feedback records the vertices in the order
* that they were inserted into the GL pipeline, not the order of
* shader completion.
*
* This test verifies that transform feedback records vertices in the
* correct order by using a vertex shader whose execution time is
* dramatically different for different vertices.
*
* The test requries two command line arguments:
*
* - drawcall indicates which drawing function should be called. A
* value of "arrays" causes DrawArrays() to be used. A value of
* "elements" causes DrawElemeents() to be used. When
* DrawElements() is used, we supply an indices array that scrambles
* the order in which vertices are sent to the shader, and verify
* that the scrambling is reflected in the transform feedback
* output.
*
* - mode indiceates which drawing mode should be used. It may be
* "triangles", "lines", or "points".
*/
#include "piglit-util-gl-common.h"
#define NUM_POINTS 10002
#define SHIFT_COUNT 64
PIGLIT_GL_TEST_CONFIG_BEGIN
config.window_width = 100;
config.window_height = 100;
config.window_visual = PIGLIT_GL_VISUAL_DOUBLE | PIGLIT_GL_VISUAL_RGB | PIGLIT_GL_VISUAL_ALPHA;
PIGLIT_GL_TEST_CONFIG_END
static GLenum draw_mode;
static GLboolean use_draw_elements;
static GLuint prog;
static GLuint xfb_buf;
static unsigned *verts;
static unsigned *indices;
/* This vertex shader computes the hailstone sequence, which is
* defined as:
*
* x[0] = starting_x
* x[n+1] = x[n]/2 if x[n] is even
* = 3*x[n]+1 if x[n] is odd
*
* The shader measures, for different values of starting_x, the
* minimum n such that x[n] = 1. This value is output in
* iteration_count. The shader outputs a copy of starting_x in
* starting_x_copy.
*
* To prevent an infinite loop, if starting_x is 0, it is changed to
* 1.
*
* In addition, to consume more execution time, the shader maintains a
* 31-bit shift register whose value starts at 1, and at each
* iteration of the algorithm, shifts it left, in circular fashion,
* shift_count times. shift_count can be adjusted as necessary to
* ensure that vertex shader threads complete out of order, but the
* entire test doesn't take too long to finish.
*
* All of this pointless mathematics serves one purpose: to ensure
* that different invocations of the vertex shader take dramatically
* different amounts of time to execute.
*/
static const char *vstext =
"#version 130\n"
"in uint starting_x;\n"
"flat out uint starting_x_copy;\n"
"flat out uint iteration_count;\n"
"flat out uint shift_reg_final;\n"
"uniform uint shift_count;\n"
"\n"
"void main()\n"
"{\n"
" gl_Position = vec4(0.0);\n"
" uint x = starting_x;\n"
" if (x == 0u)\n"
" x = 1u;\n"
" uint count = 0u;\n"
" uint shift_reg = 1u;\n"
" starting_x_copy = starting_x;\n"
" while (x != 1u) {\n"
" ++count;\n"
" if (x % 2u == 0u)\n"
" x /= 2u;\n"
" else\n"
" x = 3u * x + 1u;\n"
" uint i;\n"
" for (i = 0u; i < shift_count; ++i)\n"
" shift_reg = (shift_reg * 2u) % 0x7fffffffu;\n"
" }\n"
" iteration_count = count;\n"
" shift_reg_final = shift_reg;\n"
"}\n";
static const char *varyings[] = {
"starting_x_copy", "iteration_count", "shift_reg_final"
};
static void
initialize_shader_and_xfb()
{
GLuint vs;
piglit_require_gl_version(30);
piglit_require_GLSL_version(130);
piglit_require_transform_feedback();
vs = piglit_compile_shader_text(GL_VERTEX_SHADER, vstext);
prog = piglit_CreateProgram();
piglit_AttachShader(prog, vs);
glTransformFeedbackVaryings(prog, 3, varyings, GL_INTERLEAVED_ATTRIBS);
piglit_LinkProgram(prog);
if (!piglit_link_check_status(prog)) {
piglit_DeleteProgram(prog);
piglit_report_result(PIGLIT_FAIL);
}
glGenBuffers(1, &xfb_buf);
glBindBuffer(GL_TRANSFORM_FEEDBACK_BUFFER, xfb_buf);
glBufferData(GL_TRANSFORM_FEEDBACK_BUFFER,
3*NUM_POINTS*sizeof(unsigned), NULL, GL_STREAM_READ);
glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, xfb_buf);
piglit_UseProgram(prog);
if (!piglit_check_gl_error(0))
piglit_report_result(PIGLIT_FAIL);
}
static void
initialize_vertex_shader_inputs()
{
GLint starting_x_index = glGetAttribLocation(prog, "starting_x");
unsigned i;
verts = malloc(NUM_POINTS*sizeof(unsigned));
indices = malloc(NUM_POINTS*sizeof(unsigned));
for (i = 0; i < NUM_POINTS; ++i)
verts[i] = i;
for (i = 0; i < NUM_POINTS/2; ++i) {
indices[i] = 2*i;
indices[i + NUM_POINTS/2] = 2*i+1;
}
piglit_Uniform1ui(piglit_GetUniformLocation(prog, "shift_count"),
SHIFT_COUNT);
glVertexAttribIPointer(starting_x_index, 1, GL_UNSIGNED_INT, sizeof(unsigned),
verts);
glEnableVertexAttribArray(starting_x_index);
if (!piglit_check_gl_error(0))
piglit_report_result(PIGLIT_FAIL);
}
/**
* Compute the value of iteration_count that we expect the vertex
* shader to output for the given starting_x.
*/
static unsigned
compute_iteration_count(unsigned starting_x)
{
unsigned count = 0;
unsigned x = starting_x;
if (x == 0)
x = 1;
while (x != 1) {
++count;
if (x % 2 == 0)
x /= 2;
else
x = 3 * x + 1;
}
return count;
}
/**
* Compute the value of shift_reg_final that we expect the vertex
* shader to output for the given iteration_count.
*/
static unsigned
compute_shift_reg_final(unsigned iteration_count)
{
/* shift_reg starts at 1 and is shifted left
* SHIFT_COUNT*iteration_count times. After every 31 shifts,
* it resets to 1.
*/
return ((unsigned) 1) << ((SHIFT_COUNT * iteration_count) % 31);
}
static void
draw()
{
glEnable(GL_RASTERIZER_DISCARD);
glBeginTransformFeedback(draw_mode);
glBindBuffer(GL_ARRAY_BUFFER, 0);
if (use_draw_elements) {
glDrawElements(draw_mode, NUM_POINTS, GL_UNSIGNED_INT,
indices);
} else {
glDrawArrays(draw_mode, 0, NUM_POINTS);
}
glEndTransformFeedback();
if (!piglit_check_gl_error(0))
piglit_report_result(PIGLIT_FAIL);
}
static void
check_results_and_exit()
{
unsigned *readback;
unsigned i;
GLboolean pass = GL_TRUE;
readback = glMapBuffer(GL_TRANSFORM_FEEDBACK_BUFFER, GL_READ_ONLY);
pass = piglit_check_gl_error(0) && pass;
for (i = 0; i < NUM_POINTS; ++i) {
unsigned expected_starting_x =
use_draw_elements ? indices[i] : i;
unsigned expected_iteration_count =
compute_iteration_count(expected_starting_x);
unsigned expected_shift_reg_final =
compute_shift_reg_final(expected_iteration_count);
if (readback[3*i] != expected_starting_x) {
printf("Order changed at vertex %u\n", i);
pass = GL_FALSE;
break;
}
if (readback[3*i+1] != expected_iteration_count) {
printf("Incorrect iteration_count at vertex %u\n", i);
pass = GL_FALSE;
break;
}
if (readback[3*i+2] != expected_shift_reg_final) {
printf("Incorrect shift_reg_final at vertex %u\n", i);
pass = GL_FALSE;
break;
}
}
glUnmapBuffer(GL_TRANSFORM_FEEDBACK_BUFFER);
piglit_report_result(pass ? PIGLIT_PASS : PIGLIT_FAIL);
}
static void
print_usage_and_exit(char *prog_name)
{
printf("Usage: %s <drawcall> <mode>\n"
" where <drawcall is one of:\n"
" arrays\n"
" elements\n"
" and <mode> is one of:\n"
" triangles\n"
" lines\n"
" points\n", prog_name);
exit(1);
}
void
piglit_init(int argc, char **argv)
{
/* Interpret command line args */
if (argc != 3)
print_usage_and_exit(argv[0]);
if (strcmp(argv[1], "arrays") == 0)
use_draw_elements = GL_FALSE;
else if (strcmp(argv[1], "elements") == 0)
use_draw_elements = GL_TRUE;
else
print_usage_and_exit(argv[0]);
if (strcmp(argv[2], "triangles") == 0)
draw_mode = GL_TRIANGLES;
else if (strcmp(argv[2], "lines") == 0)
draw_mode = GL_LINES;
else if (strcmp(argv[2], "points") == 0)
draw_mode = GL_POINTS;
else
print_usage_and_exit(argv[0]);
initialize_shader_and_xfb();
initialize_vertex_shader_inputs();
draw();
check_results_and_exit();
}
enum piglit_result piglit_display(void)
{
/* Test should finish before we reach here. */
return PIGLIT_FAIL;
}
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