From ab07b548fe02198557f6ae3c875dcefbf92fc044 Mon Sep 17 00:00:00 2001
From: Paul Ferrand <paulfd@outlook.fr>
Date: Tue, 10 Dec 2019 00:01:15 +0100
Subject: [PATCH] Added a way to get an envelope with quantized jumps

---
 src/sfizz/LinearEnvelope.cpp | 40 +++++++++++++++++++++++++++++++++++-
 src/sfizz/LinearEnvelope.h   |  8 ++++++++
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/src/sfizz/LinearEnvelope.cpp b/src/sfizz/LinearEnvelope.cpp
index c9c04d44..3c9dc975 100644
--- a/src/sfizz/LinearEnvelope.cpp
+++ b/src/sfizz/LinearEnvelope.cpp
@@ -100,4 +100,42 @@ void LinearEnvelope<Type>::getBlock(absl::Span<Type> output)
     clear();
 }
 
-}
\ No newline at end of file
+template <class Type>
+void LinearEnvelope<Type>::getQuantizedBlock(absl::Span<Type> output, Type quantizationStep)
+{
+    absl::c_sort(events, [](const auto& lhs, const auto& rhs) {
+        return lhs.first < rhs.first;
+    });
+    int index { 0 };
+
+    auto quantize = [quantizationStep](Type value) -> Type {
+        return static_cast<int>(value / quantizationStep) * quantizationStep;
+    }
+
+    currentValue = quantize(currentValue);
+    const auto outputSize = static_cast<int>(output.size());
+    for (auto& event : events) {
+        const auto length = min(event.first, outputSize) - index;
+        const auto newValue = quantize(event.second);
+
+        if (length == 0) {
+            currentValue = newValue;
+            continue;
+        }
+
+        const int numSteps = abs(newValue - currentValue) / quantizationStep;
+        const auto stepLength = static_cast<int>(length / numSteps);
+        while (outputSize - index > stepLength) {
+            currentValue += currentValue <= newValue ? quantizationStep : -quantizationStep;
+            fill<Type>(output.subspan(index, stepLength), currentValue);
+            index += stepLength;
+        }
+    }
+
+    if (index < outputSize)
+        fill<Type>(output.subspan(index), currentValue);
+
+    clear();
+}
+
+}
diff --git a/src/sfizz/LinearEnvelope.h b/src/sfizz/LinearEnvelope.h
index d69562c3..545b6c56 100644
--- a/src/sfizz/LinearEnvelope.h
+++ b/src/sfizz/LinearEnvelope.h
@@ -99,6 +99,14 @@ public:
      * @param output
      */
     void getBlock(absl::Span<Type> output);
+    /**
+     * @brief  Get a block of interpolated values with a forced quantization. The
+     * values within the block will vary in quantization steps.
+     *
+     * @param output
+     * @param quantizationStep
+     */
+    void getQuantizedBlock(absl::Span<Type> output, Type quantizationStep);
 private:
     std::function<Type(Type)> function { [](Type input) { return input; } };
     static_assert(std::is_arithmetic<Type>::value, "Type should be arithmetic");