lineshaderhorizontal.frag

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// Copyright (C) 2025 The Qt Company Ltd.

// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only

#version 440

layout(location = 0) in vec2 texCoord;

layout(location = 1) in vec2 fragCoord;

layout(location = 0) out vec4 fragColor;

layout(std140, binding = 0) uniform buf {

    mat4 qt_Matrix;

    float qt_Opacity;

    vec3 iResolution;

    vec4 color;

    float lineWidth;

    float smoothing;

};

#define HORIZONTAL 1

float createBars(float coord, float spacing, float strokeWidth) {

    float sbar = 1.0 / spacing;

    float barWidth = strokeWidth / spacing;

    float firstPos = ((barWidth + smoothing / spacing) * 1.0);

    float p = firstPos + coord * sbar;

    //float p = (coord - 0.5) * sbar;

    float bar = abs(2.0 * fract(p) - 1.0);

    float barSmoothness = smoothing / spacing;

    bar = smoothstep(1.0 - barWidth - barSmoothness, 1.0 - barWidth + barSmoothness, bar);

    return bar;

void main() {

        float line = 0.0;

    #if (HORIZONTAL == 1)

        float spacing = iResolution.y * 0.5 + lineWidth + smoothing;

        line += createBars(fragCoord.y, spacing, lineWidth);

    #else

        float spacing = iResolution.x * 0.5 + lineWidth + smoothing;

        line += createBars(fragCoord.x, spacing, lineWidth);

    #endif

        vec3 lineColor = vec3(0.0);

        float alpha = line * color.a;

        lineColor = mix(lineColor, color.rgb, alpha);

        fragColor = vec4(lineColor, alpha);

    fragColor = fragColor * qt_Opacity;