#version 450
/* Copyright (c) 2020 Themaister
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

layout(location = 0) out vec2 vUV;

layout(push_constant) uniform UBO
{
    float y_offset;
} registers;

void main()
{
    if (gl_VertexIndex == 0)
        gl_Position = vec4(-1.0, -1.0, 0.0, 1.0);
    else if (gl_VertexIndex == 1)
        gl_Position = vec4(-1.0, +3.0, 0.0, 1.0);
    else
        gl_Position = vec4(+3.0, -1.0, 0.0, 1.0);

    vUV = vec2(gl_Position.x * 0.5 + 0.5, gl_Position.y * 0.5 + 0.5 + registers.y_offset);
}