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/*
Copyright (c) 2019 The Khronos Group Inc.
Use of this source code is governed by an MIT-style license that can be
found in the LICENSE.txt file.
*/
#ifdef GL_ES
precision mediump float;
#endif
/* This epsilon will work as long as the magnitude of the float is < 128.
* This can be seen by taking the spec relative mediump precision of 2^-10:
* 0.125 / 2^-10 = 128
*/
#define ERROR_EPSILON (0.125)
void main (void)
{
float x;
// Declare a 3 by 3 matrix with unique elements.
mat3 a = mat3( 1.0, 2.0, 3.0,
4.0, 5.0, 6.0,
7.0, 8.0, 9.0);
// Check each element.
bool elms = true;
if(a[0][0] != 1.0) elms = false;
if(a[0][1] != 2.0) elms = false;
if(a[0][2] != 3.0) elms = false;
if(a[1][0] != 4.0) elms = false;
if(a[1][1] != 5.0) elms = false;
if(a[1][2] != 6.0) elms = false;
if(a[2][0] != 7.0) elms = false;
if(a[2][1] != 8.0) elms = false;
if(a[2][2] != 9.0) elms = false;
// Add up each row.
bool rows = true;
x = a[0][0] + a[1][0] + a[2][0];
if( x < 12.0-ERROR_EPSILON || x > 12.0+ERROR_EPSILON ) rows = false;
x = a[0][1] + a[1][1] + a[2][1];
if(x < 15.0-ERROR_EPSILON || x > 15.0+ERROR_EPSILON ) rows = false;
x = a[0][2] + a[1][2] + a[2][2];
if(x < 18.0-ERROR_EPSILON || x > 18.0+ERROR_EPSILON ) rows = false;
// Add up each column of the copy.
bool cols = true;
x = a[0][0] + a[0][1] + a[0][2];
if( x < 6.0-ERROR_EPSILON || x > 6.0+ERROR_EPSILON ) cols = false;
x = a[1][0] + a[1][1] + a[1][2];
if(x < 15.0-ERROR_EPSILON || x > 15.0+ERROR_EPSILON) cols = false;
x = a[2][0] + a[2][1] + a[2][2];
if(x < 24.0-ERROR_EPSILON || x > 24.0+ERROR_EPSILON) cols = false;
// Check if all of the operations were successful.
float gray = elms && rows && cols ? 1.0 : 0.0;
// Assign the fragment color.
gl_FragColor = vec4(gray, gray, gray, 1.0);
}