chromakey: add invert mask option

app/node/keying/chromakey/chromakey.cpp

@@ -24,6 +24,7 @@ namespace olive {
 
 const QString ChromaKeyNode::kColorInput = QStringLiteral("color_key");
 const QString ChromaKeyNode::kMaskOnlyInput = QStringLiteral("mask_only_in");
+const QString ChromaKeyNode::kInvertInput = QStringLiteral("invert_in");
 const QString ChromaKeyNode::kUpperToleranceInput = QStringLiteral("upper_tolerence_in");
 const QString ChromaKeyNode::kLowerToleranceInput = QStringLiteral("lower_tolerence_in");
 const QString ChromaKeyNode::kGarbageMatteInput = QStringLiteral("garbage_in");
@@ -59,6 +60,8 @@ ChromaKeyNode::ChromaKeyNode()
   SetInputProperty(kShadowsInput, QStringLiteral("min"), 0.0);
   SetInputProperty(kShadowsInput, QStringLiteral("base"), 0.1);
 
+  AddInput(kInvertInput, NodeValue::kBoolean, false);
+
   AddInput(kMaskOnlyInput, NodeValue::kBoolean, false);
 }
 
@@ -93,6 +96,7 @@ void ChromaKeyNode::Retranslate()
   SetInputName(kHighlightsInput, tr("Highlights"));
   SetInputName(kUpperToleranceInput, tr("Upper Tolerance"));
   SetInputName(kLowerToleranceInput, tr("Lower Tolerance"));
+  SetInputName(kInvertInput, tr("Invert Mask"));
   SetInputName(kMaskOnlyInput, tr("Show Mask Only"));
 }
 

app/node/keying/chromakey/chromakey.h

@@ -42,6 +42,7 @@ class ChromaKeyNode : public OCIOBaseNode {
   virtual void ConfigChanged() override;
 
   static const QString kColorInput;
+  static const QString kInvertInput;
   static const QString kMaskOnlyInput;
   static const QString kUpperToleranceInput;
   static const QString kLowerToleranceInput;

app/shaders/chromakey.frag

@@ -9,6 +9,7 @@ uniform sampler2D garbage_in;
 uniform sampler2D core_in;
 uniform bool garbage_in_enabled;
 uniform bool core_in_enabled;
+uniform bool invert_in;
 
 uniform float highlights_in;
 uniform float shadows_in;
@@ -94,6 +95,11 @@ void main() {
   mask = shadows_in * 0.01 * (highlights_in * 0.01 * mask - 1.0) + 1.0;
   mask = clamp(mask, 0.0, 1.0);
 
+  // Invert
+  if (invert_in) {
+    mask = 1.0 - mask;
+  }
+
   col.rgb *= mask;
   col.w = mask;