photosurface demo: Add a procedural texture background

Adapted from https://www.shadertoy.com/view/WdscWN via the Qt Quick
Effects Maker and further tweaking by hand.

Because we do not have a defined pattern to compile shaders from sources
with qmake, building this demo with qmake is no longer supported.

Task-number: QTBUG-108924
Change-Id: I0b19b6aa9865f2e8c259fb1d12dffd9a28eae72e
Reviewed-by: Oliver Eftevaag <oliver.eftevaag@qt.io>
(cherry picked from commit b766d2f1570825092bdb58ded83f7de9aa45b533)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

6 files changed, 110 insertions, 21 deletions

diff --git a/examples/demos/demos.pro b/examples/demos/demos.pro
index 62046935..5622baa5 100644
--- a/examples/demos/demos.pro
+++ b/examples/demos/demos.pro
@@ -7,7 +7,6 @@ qtHaveModule(quick) {
         clocks \
         tweetsearch \
         maroon \
-        photosurface \
         stocqt
 
     qtHaveModule(quickcontrols2) {
diff --git a/examples/demos/photosurface/CMakeLists.txt b/examples/demos/photosurface/CMakeLists.txt
index d696882f..d60b9d18 100644
--- a/examples/demos/photosurface/CMakeLists.txt
+++ b/examples/demos/photosurface/CMakeLists.txt
@@ -12,7 +12,7 @@ endif()
 
 set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/demos/photosurface")
 
-find_package(Qt6 REQUIRED COMPONENTS Core Gui Qml Quick)
+find_package(Qt6 REQUIRED COMPONENTS Core Gui Qml Quick ShaderTools)
 
 qt_standard_project_setup(REQUIRES 6.5)
 
@@ -55,6 +55,16 @@ qt_add_qml_module(photosurfaceexample
       "resources/folder.png"
 )
 
+qt6_add_shaders(photosurfaceexample "shaders"
+    BATCHABLE
+    PRECOMPILE
+    OPTIMIZED
+    PREFIX
+        "/qt/qml/photosurface"
+    FILES
+        "resources/shaders/gneiss.frag"
+)
+
 install(TARGETS photosurfaceexample
     RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
     BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}"
diff --git a/examples/demos/photosurface/photosurface.pro b/examples/demos/photosurface/photosurface.pro
deleted file mode 100644
index 21c2214b..00000000
--- a/examples/demos/photosurface/photosurface.pro
+++ /dev/null
@@ -1,12 +0,0 @@
-TEMPLATE = app
-
-QT += qml quick
-SOURCES += main.cpp
-RESOURCES += photosurface.qrc
-
-target.path = $$[QT_INSTALL_EXAMPLES]/demos/photosurface
-INSTALLS += target
-ICON = resources/icon.png
-macos: ICON = resources/photosurface.icns
-win32: RC_FILE = resources/photosurface.rc
-
diff --git a/examples/demos/photosurface/photosurface.qml b/examples/demos/photosurface/photosurface.qml
index 7b4fd1d0..c70e0b34 100644
--- a/examples/demos/photosurface/photosurface.qml
+++ b/examples/demos/photosurface/photosurface.qml
@@ -25,6 +25,13 @@ Window {
         onAccepted: folderModel.folder = selectedFolder
     }
 
+    ShaderEffect {
+        readonly property vector3d iResolution: Qt.vector3d(width, height, 1.0)
+
+        fragmentShader: "resources/shaders/gneiss.frag.qsb"
+        anchors.fill: parent
+    }
+
     ScrollView {
         id: flick
         anchors.fill: parent
diff --git a/examples/demos/photosurface/photosurface.qrc b/examples/demos/photosurface/photosurface.qrc
deleted file mode 100644
index 9834eecb..00000000
--- a/examples/demos/photosurface/photosurface.qrc
+++ /dev/null
@@ -1,7 +0,0 @@
-<RCC>
-    <qresource prefix="/qt/qml/photosurface">
-        <file>photosurface.qml</file>
-        <file>resources/folder.png</file>
-        <file>resources/MomentumAnimation.qml</file>
-    </qresource>
-</RCC>
diff --git a/examples/demos/photosurface/resources/shaders/gneiss.frag b/examples/demos/photosurface/resources/shaders/gneiss.frag
new file mode 100644
index 00000000..67e3caaa
--- /dev/null
+++ b/examples/demos/photosurface/resources/shaders/gneiss.frag
@@ -0,0 +1,92 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+// simplified from https://www.shadertoy.com/view/WdscWN
+
+#version 450
+
+layout(location = 0) in vec2 qt_TexCoord0;
+layout(location = 0) out vec4 fragColor;
+layout(std140, binding = 0) uniform buf {
+    mat4 qt_Matrix;
+    float qt_Opacity;
+    vec2 iResolution;
+};
+
+const float mag = 12.0;
+
+// this function is from https://www.shadertoy.com/view/4djSRW
+int hash12(vec2 p, float num_colors)
+{
+    // set the number of colors to be randomly generated
+    vec3 p3 = fract(vec3(p.xyx) * 0.1031);
+    p3 += dot(p3, p3.yzx + 33.33);
+    return int(floor(fract((p3.x + p3.y) * p3.z) * num_colors));
+}
+
+int magnify(vec2 fragCoord, float mag, float num_colors) {
+    for (float i = 1.0; i < mag; i++) {
+        fragCoord += vec2(sin(fragCoord.y / (100.0 * i)) * 10.0,
+                          sin(fragCoord.x / (100.0 * mag * i)) * 10.0) * mag * mag;
+    }
+
+    return hash12(floor(fragCoord / pow(3.0, mag)), num_colors);
+}
+
+ivec4 get_neighbors(vec2 fragCoord, float mag, float colors) {
+    return ivec4(magnify(fragCoord+vec2(0, 1), mag, colors),
+        magnify(fragCoord+vec2(1, 0), mag, colors),
+        magnify(fragCoord-vec2(0, 1), mag, colors),
+        magnify(fragCoord-vec2(1, 0), mag, colors));
+}
+
+bool is_next_to(int color, ivec4 neighbors) {
+    return (neighbors.x == color)
+        || (neighbors.y == color)
+        || (neighbors.z == color)
+        || (neighbors.w == color);
+}
+
+int next_biome(inout int color1, ivec4 neighbors) {
+    return (color1 == 0 && is_next_to(2, neighbors)) ? 3
+         : (color1 == 3 && is_next_to(2, neighbors)) ? 4
+         : (color1 == 2) ? 0
+         : (color1 == 1 && is_next_to(0, neighbors)) ? 0
+         : (color1 == 4 && is_next_to(0, neighbors)) ? 0
+         : color1;
+}
+
+int biome(in vec2 fragCoord, float mag, int colors[5]) {
+    float num_colors = float(colors.length());
+    int color1 = magnify(fragCoord, mag, num_colors);
+    ivec4 neighbors;
+    while(mag > 1.0) {
+        neighbors = get_neighbors(fragCoord, mag, num_colors);
+        color1 = next_biome(color1, neighbors);
+        mag -= 1.0;
+    }
+    return colors[int(color1)];
+}
+
+void main() {
+    vec2 fc = qt_TexCoord0 * iResolution.y * mag;
+    vec2 uv = qt_TexCoord0;
+
+    switch (biome(fc, mag, int[](0, 1, 2, 3, 4))) {
+        case 0:
+            fragColor = vec4(0.2, 0.2, 0.24, 1.0);
+            break;
+        case 1:
+            fragColor = vec4(0.24, 0.16, 0.28, 1.0);
+            break;
+        case 2:
+            fragColor = vec4(0.16, 0.18, 0.22, 1.0);
+            break;
+        case 3:
+            fragColor = vec4(0.10, 0.10, 0.10, 1.0);
+            break;
+        default:
+            fragColor = vec4(0.0, 0.252, 0.27, 1.0);
+            break;
+    }
+    fragColor *= (0.35 + 0.65 * sin(uv.x * 2.35)) * (0.35 + 0.65 * sin(uv.y * 4.2)) * qt_Opacity;
+}