/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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#version 120

uniform sampler2D leavingSlideTexture;
uniform sampler2D enteringSlideTexture;
uniform float time;
varying vec2 v_texturePosition;

void main() {
    vec4 black = vec4(0.0, 0.0, 0.0, 1.0);
    vec4 texel;
    float amount;
    if (time < 0.5) {
        texel = texture2D(leavingSlideTexture, v_texturePosition);
        amount = time * 2;
    } else {
        texel = texture2D(enteringSlideTexture, v_texturePosition);
        amount = (1.0 - time) * 2;
    }
    gl_FragColor = mix(texel, black, amount);
}

/* vim:set shiftwidth=4 softtabstop=4 expandtab: */