[require]
GLSL >= 1.20

[vertex shader]
#version 120
attribute vec3 vertex;
uniform mat4 mvp = mat4(1.);

void main()
{
    vec4 tmp;

#if 1
    tmp.x = vertex.x;
    tmp.y = vertex.y;
    tmp.z = vertex.z;
    tmp[3] = 1.0;
#else
    tmp.xyz = vertex;
    tmp.w = 1.0;
#endif
    gl_Position = mvp * tmp;
}

[fragment shader]
void main()
{
    gl_FragColor = vec4(0., 1., 0., 1.);
}

[vertex data]
vertex/float/3
 1.0  1.0  1.0
-1.0  1.0  1.0
-1.0 -1.0  1.0
 1.0 -1.0  1.0

[test]
draw arrays GL_TRIANGLE_FAN 0 4
relative probe rgb (.5, .5) (0.0, 1.0, 0.0)