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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;
// Function declaration.
vec4 function(in vec4 par);
bool is_all(const in vec4 par, const in float value);
void set_all(out vec4 par, const in float value);
void main (void)
{
vec4 par = vec4(1.0, 1.0, 1.0, 1.0);
vec4 ret = vec4(0.0, 0.0, 0.0, 0.0);
float gray = 0.0;
ret = function(par);
// The parameter should remain unchanged by the function and the function should return 1.0.
if(is_all(par, 1.0) && is_all(ret, 1.0))
{
gray = 1.0;
}
color = vec4(gray, gray, gray, 1.0);
gl_Position = gtf_ModelViewProjectionMatrix * gtf_Vertex;
}
// Function definition.
vec4 function(in vec4 par)
{
// Return the value of the parameter.
if(is_all(par, 1.0))
{
// Test parameter qualifier (default is "in").
set_all(par, 0.0);
return vec4(1.0, 1.0, 1.0, 1.0);
}
else
return vec4(0.0, 0.0, 0.0, 0.0);
}
bool is_all(const in vec4 par, const in float value)
{
bool ret = true;
if(par[0] != value)
ret = false;
if(par[1] != value)
ret = false;
if(par[2] != value)
ret = false;
if(par[3] != value)
ret = false;
return ret;
}
void set_all(out vec4 par, const in float value)
{
par[0] = value;
par[1] = value;
par[2] = value;
par[3] = value;
}
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