qt-everywhere-src-5.15.1/qtquick3d/src/imports/effectlib/shaders/edgedetect.vert

varying vec4 TexCoordBLL; // Bottom Left and Bottom Tap
varying vec4 TexCoordTLT; // Top Left and Top Tap
varying vec4 TexCoordTRR; // Upper Right and Right Tap
varying vec4 TexCoordBRB; // Bottom Right and Bottom Tap

void vert()
{
    vec2 delta = vec2(1.0 / Texture0Info.x, 1.0 / Texture0Info.y);
    TexCoordBLL = vec4(TexCoord.st, TexCoord.st) + vec4(-delta.xy, -delta.x, 0);
    TexCoordTLT = vec4(TexCoord.st, TexCoord.st) + vec4(-delta.x, delta.y, 0, delta.y);
    TexCoordTRR = vec4(TexCoord.st, TexCoord.st) + vec4(delta.xy, delta.x, 0);
    TexCoordBRB = vec4(TexCoord.st, TexCoord.st) + vec4(delta.x, -delta.y, 0, -delta.y);
}