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path: root/tests/spec/glsl-1.20/execution/vs-mix-as-condition.shader_test
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[require]
GLSL >= 1.20

[vertex shader]
uniform vec4 red = vec4(1.0, 0.0, 0.0, 1.0);
uniform vec4 color_delta = vec4(-1.0, 1.0, 0.0, 0.0);
uniform float a = -1.0;
uniform float b = 1.0;
uniform float c = 0.5;

attribute vec4 piglit_vertex;
varying vec4 color;

void main()
{
    gl_Position = piglit_vertex;

    color = red;

    /* This attempts to reproduce a bug in the i965 vec4 backend.  Three-
     * source instructions, like LRP, cannot write to the null register.
     * However, when the result is only used in a condition, the write can be
     * (erroneously) eliminated.
     */
    if (mix(a, b, c) == 0)
        color += color_delta;
}

[fragment shader]
varying vec4 color;

void main()
{
    gl_FragColor = color;
}

[test]
draw rect -1 -1 2 2
probe all rgba 0.0 1.0 0.0 1.0