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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.
*/
attribute vec4 gtf_Vertex;
uniform mat4 gtf_ModelViewProjectionMatrix;
varying vec4 color;
#define ERROR_EPSILON 0.1
void main (void)
{
float x;
// Declare a 3 by 3 matrix with unique elements.
mat3 a = mat3( 1.0, 2.0, 4.0, // 1.0 8.0 64.0
8.0, 16.0, 32.0, // 2.0 16.0 128.0
64.0, 128.0, 256.0); // 4.0 32.0 256.0
// 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] != 4.0) elms = false;
if(a[1][0] != 8.0) elms = false;
if(a[1][1] != 16.0) elms = false;
if(a[1][2] != 32.0) elms = false;
if(a[2][0] != 64.0) elms = false;
if(a[2][1] != 128.0) elms = false;
if(a[2][2] != 256.0) elms = false;
// Add up each row.
bool rows = true;
x = a[0][0] + a[1][0] + a[2][0];
if( x < 73.0-ERROR_EPSILON || x > 73.0+ERROR_EPSILON ) rows = false;
x = a[0][1] + a[1][1] + a[2][1];
if(x < 146.0-ERROR_EPSILON || x > 146.0+ERROR_EPSILON ) rows = false;
x = a[0][2] + a[1][2] + a[2][2];
if(x < 292.0-ERROR_EPSILON || x > 292.0+ERROR_EPSILON ) rows = false;
// Add up each column.
bool cols = true;
x = a[0][0] + a[0][1] + a[0][2];
if( x < 7.0-ERROR_EPSILON || x > 7.0+ERROR_EPSILON ) cols = false;
x = a[1][0] + a[1][1] + a[1][2];
if(x < 56.0-ERROR_EPSILON || x > 56.0+ERROR_EPSILON) cols = false;
x = a[2][0] + a[2][1] + a[2][2];
if(x < 448.0-ERROR_EPSILON || x > 448.0+ERROR_EPSILON) cols = false;
// Check if all of the operations were successful.
float gray = elms && rows && cols ? 1.0 : 0.0;
// Assign the varying variable color.
color = vec4(gray, gray, gray, 1.0);
// Transform the vertex position.
gl_Position = gtf_ModelViewProjectionMatrix * gtf_Vertex;
}