[orx-fx] Add BlendSpectral

orx-fx/src/commonMain/kotlin/blend/BlendSpectral.kt

@@ -0,0 +1,104 @@
+package org.openrndr.extra.fx.blend
+
+import org.openrndr.draw.Filter2to1
+import org.openrndr.draw.filterShaderFromCode
+import org.openrndr.extra.fx.fx_spectral
+import org.openrndr.extra.parameters.BooleanParameter
+import org.openrndr.extra.parameters.Description
+import org.openrndr.extra.parameters.DoubleParameter
+
+private val spectralBlendShader = """// includes    
+${fx_spectral}
+// filter code
+uniform sampler2D tex0;
+uniform sampler2D tex1;
+in vec2 v_texCoord0;
+
+out vec4 o_color;
+
+uniform bool linearizeInputA;
+uniform bool linearizeInputB;
+uniform bool delinearizeOutput;
+uniform float fill;
+uniform bool clip;
+
+vec3 srgb_to_linear(vec3 c) {
+    const float t = 0.00313066844250063;
+    return vec3(
+        c.r <= t ? c.r / 12.92 : pow((c.r + 0.055) / 1.055, 2.4),
+        c.g <= t ? c.g / 12.92 : pow((c.g + 0.055) / 1.055, 2.4),
+        c.b <= t ? c.b / 12.92 : pow((c.b + 0.055) / 1.055, 2.4));
+}
+
+vec3 linear_to_srgb(vec3 c) {
+    const float t = 0.00313066844250063;
+    return vec3(
+        c.r <= t ? c.r * 12.92 : 1.055 * pow(c.r, 1 / 2.4) - 0.055,
+        c.g <= t ? c.g * 12.92 : 1.055 * pow(c.g, 1 / 2.4) - 0.055,
+        c.b <= t ? c.b * 12.92 : 1.055 * pow(c.b, 1 / 2.4) - 0.055
+    );
+}
+
+void main() {
+    vec4 a = texture(tex0, v_texCoord0);
+    vec4 b = texture(tex1, v_texCoord0);
+    if (linearizeInputA) {
+        a.rgb = srgb_to_linear(a.rgb);
+    }
+    
+    if (linearizeInputB) {
+        b.rgb = srgb_to_linear(b.rgb);
+    }
+    
+    // depremultiply alpha
+    vec3 na = a.a == 0.0 ? vec3(0.0): a.rgb / a.a;
+    vec3 nb = b.a == 0.0 ? vec3(0.0): b.rgb / b.a;
+
+    vec4 mixed = vec4(spectral_mix(na, nb, min(1.0,  b.a * fill) ), min(a.a, b.a));
+
+    // premultiply alpha
+    mixed.rgb *= mixed.a;    
+    
+    if (!clip) {
+        vec4 b_over_a = a * (1.0 - b.a) + b;    
+        mixed = b_over_a * (1.0-mixed.a)  + mixed;
+    }
+
+    if (delinearizeOutput) {
+         mixed.rgb = linear_to_srgb(mixed.rgb);
+    }
+
+    o_color = mixed;
+}
+ 
+"""
+
+/**
+ * Blend based on pigment simulation
+ */
+@Suppress("RUNTIME_ANNOTATION_NOT_SUPPORTED")
+@Description("Blend spectral")
+class BlendSpectral : Filter2to1(filterShaderFromCode(spectralBlendShader, "color-burn")) {
+    @BooleanParameter("source clip")
+    var clip: Boolean by parameters
+
+    @BooleanParameter("linearize input A")
+    var linearizeInputA: Boolean by parameters
+
+    @BooleanParameter("linearize input B")
+    var linearizeInputB: Boolean by parameters
+
+    @BooleanParameter("delinearize output")
+    var delinearizeOutput: Boolean by parameters
+
+    @DoubleParameter("fill", 0.0, 1.0)
+    var fill: Double by parameters
+
+    init {
+        clip = false
+        linearizeInputA = true
+        linearizeInputB = true
+        delinearizeOutput = true
+        fill = 1.0
+    }
+}