feat: add curve inputs and raise uniform limit for GLSL shader node (#13158)

* feat: add curve inputs and raise uniform limit for GLSL shader node

* allow arbitrary size for curve

blueprints/.glsl/Color_Balance_15.frag

@@ -0,0 +1,90 @@
+#version 300 es
+precision highp float;
+
+uniform sampler2D u_image0;
+uniform float u_float0;
+uniform float u_float1;
+uniform float u_float2;
+uniform float u_float3;
+uniform float u_float4;
+uniform float u_float5;
+uniform float u_float6;
+uniform float u_float7;
+uniform float u_float8;
+uniform bool u_bool0;
+
+in vec2 v_texCoord;
+out vec4 fragColor;
+
+vec3 rgb2hsl(vec3 c) {
+    float maxC = max(c.r, max(c.g, c.b));
+    float minC = min(c.r, min(c.g, c.b));
+    float l = (maxC + minC) * 0.5;
+    if (maxC == minC) return vec3(0.0, 0.0, l);
+    float d = maxC - minC;
+    float s = l > 0.5 ? d / (2.0 - maxC - minC) : d / (maxC + minC);
+    float h;
+    if (maxC == c.r) {
+        h = (c.g - c.b) / d + (c.g < c.b ? 6.0 : 0.0);
+    } else if (maxC == c.g) {
+        h = (c.b - c.r) / d + 2.0;
+    } else {
+        h = (c.r - c.g) / d + 4.0;
+    }
+    h /= 6.0;
+    return vec3(h, s, l);
+}
+
+float hue2rgb(float p, float q, float t) {
+    if (t < 0.0) t += 1.0;
+    if (t > 1.0) t -= 1.0;
+    if (t < 1.0 / 6.0) return p + (q - p) * 6.0 * t;
+    if (t < 1.0 / 2.0) return q;
+    if (t < 2.0 / 3.0) return p + (q - p) * (2.0 / 3.0 - t) * 6.0;
+    return p;
+}
+
+vec3 hsl2rgb(vec3 hsl) {
+    float h = hsl.x, s = hsl.y, l = hsl.z;
+    if (s == 0.0) return vec3(l);
+    float q = l < 0.5 ? l * (1.0 + s) : l + s - l * s;
+    float p = 2.0 * l - q;
+    return vec3(
+        hue2rgb(p, q, h + 1.0 / 3.0),
+        hue2rgb(p, q, h),
+        hue2rgb(p, q, h - 1.0 / 3.0)
+    );
+}
+
+void main() {
+    vec4 tex = texture(u_image0, v_texCoord);
+    vec3 color = tex.rgb;
+
+    vec3 shadows = vec3(u_float0, u_float1, u_float2) * 0.01;
+    vec3 midtones = vec3(u_float3, u_float4, u_float5) * 0.01;
+    vec3 highlights = vec3(u_float6, u_float7, u_float8) * 0.01;
+
+    float maxC = max(color.r, max(color.g, color.b));
+    float minC = min(color.r, min(color.g, color.b));
+    float lightness = (maxC + minC) * 0.5;
+
+    // GIMP weight curves: linear ramps with constants a=0.25, b=0.333, scale=0.7
+    const float a = 0.25;
+    const float b = 0.333;
+    const float scale = 0.7;
+
+    float sw = clamp((lightness - b) / -a + 0.5, 0.0, 1.0) * scale;
+    float mw = clamp((lightness - b) / a + 0.5, 0.0, 1.0) *
+               clamp((lightness + b - 1.0) / -a + 0.5, 0.0, 1.0) * scale;
+    float hw = clamp((lightness + b - 1.0) / a + 0.5, 0.0, 1.0) * scale;
+
+    color += sw * shadows + mw * midtones + hw * highlights;
+
+    if (u_bool0) {
+        vec3 hsl = rgb2hsl(clamp(color, 0.0, 1.0));
+        hsl.z = lightness;
+        color = hsl2rgb(hsl);
+    }
+
+    fragColor = vec4(clamp(color, 0.0, 1.0), tex.a);
+}

blueprints/.glsl/Color_Curves_8.frag

@@ -0,0 +1,46 @@
+#version 300 es
+precision highp float;
+
+uniform sampler2D u_image0;
+uniform sampler2D u_curve0;  // RGB master curve (256x1 LUT)
+uniform sampler2D u_curve1;  // Red channel curve
+uniform sampler2D u_curve2;  // Green channel curve
+uniform sampler2D u_curve3;  // Blue channel curve
+
+in vec2 v_texCoord;
+layout(location = 0) out vec4 fragColor0;
+
+// GIMP-compatible curve lookup with manual linear interpolation.
+// Matches gimp_curve_map_value_inline() from gimpcurve-map.c:
+//   index = value * (n_samples - 1)
+//   f = fract(index)
+//   result = (1-f) * samples[floor] + f * samples[ceil]
+//
+// Uses texelFetch (NEAREST) to avoid GPU half-texel offset issues
+// that occur with texture() + GL_LINEAR on small 256x1 LUTs.
+float applyCurve(sampler2D curve, float value) {
+    value = clamp(value, 0.0, 1.0);
+
+    float pos = value * 255.0;
+    int lo = int(floor(pos));
+    int hi = min(lo + 1, 255);
+    float f = pos - float(lo);
+
+    float a = texelFetch(curve, ivec2(lo, 0), 0).r;
+    float b = texelFetch(curve, ivec2(hi, 0), 0).r;
+
+    return a + f * (b - a);
+}
+
+void main() {
+    vec4 color = texture(u_image0, v_texCoord);
+
+    // GIMP order: per-channel curves first, then RGB master curve.
+    // See gimp_curve_map_pixels() default case in gimpcurve-map.c:
+    //   dest = colors_curve( channel_curve( src ) )
+    color.r = applyCurve(u_curve0, applyCurve(u_curve1, color.r));
+    color.g = applyCurve(u_curve0, applyCurve(u_curve2, color.g));
+    color.b = applyCurve(u_curve0, applyCurve(u_curve3, color.b));
+
+    fragColor0 = vec4(color.rgb, color.a);
+}