Add loop point crossfading in the sample editor.

src/engine/sample.h

@@ -287,6 +287,7 @@ struct DivSample {
    */
   void convert(DivSampleDepth newDepth);
 
+  
   /**
    * initialize the rest of sample formats for this sample.
    */

src/gui/doAction.cpp

@@ -1336,6 +1336,10 @@ void FurnaceGUI::doAction(int what) {
       MARK_MODIFIED;
       break;
     }
+    case GUI_ACTION_SAMPLE_XFADE_LOOP:
+      if (curSample<0 || curSample>=(int)e->song.sample.size()) break;
+      openSampleXFadeOpt=true;
+      break;
     case GUI_ACTION_SAMPLE_FILTER:
       if (curSample<0 || curSample>=(int)e->song.sample.size()) break;
       openSampleFilterOpt=true;

src/gui/gui.cpp

@@ -7529,6 +7529,8 @@ FurnaceGUI::FurnaceGUI():
   sampleFilterRes(0.25f),
   sampleFilterCutStart(16000.0f),
   sampleFilterCutEnd(100.0f),
+  sampleXFadeLoopLength(0),
+  sampleXFadeLoopLaw(50000),
   sampleFilterPower(1),
   sampleClipboard(NULL),
   sampleClipboardLen(0),
@@ -7537,6 +7539,7 @@ FurnaceGUI::FurnaceGUI():
   openSampleAmplifyOpt(false),
   openSampleSilenceOpt(false),
   openSampleFilterOpt(false),
+  openSampleXFadeOpt(false),
   selectedPortSet(0x1fff),
   selectedSubPort(-1),
   hoveredPortSet(0x1fff),

src/gui/gui.h

@@ -722,6 +722,7 @@ enum FurnaceGUIActions {
   GUI_ACTION_SAMPLE_INVERT,
   GUI_ACTION_SAMPLE_SIGN,
   GUI_ACTION_SAMPLE_FILTER,
+  GUI_ACTION_SAMPLE_XFADE_LOOP,
   GUI_ACTION_SAMPLE_PREVIEW,
   GUI_ACTION_SAMPLE_STOP_PREVIEW,
   GUI_ACTION_SAMPLE_ZOOM_IN,
@@ -2103,10 +2104,11 @@ class FurnaceGUI {
   ImVec2 sampleDragAreaSize;
   unsigned int sampleDragLen;
   float sampleFilterL, sampleFilterB, sampleFilterH, sampleFilterRes, sampleFilterCutStart, sampleFilterCutEnd;
+  int sampleXFadeLoopLength, sampleXFadeLoopLaw;
   unsigned char sampleFilterPower;
   short* sampleClipboard;
   size_t sampleClipboardLen;
-  bool openSampleResizeOpt, openSampleResampleOpt, openSampleAmplifyOpt, openSampleSilenceOpt, openSampleFilterOpt;
+  bool openSampleResizeOpt, openSampleResampleOpt, openSampleAmplifyOpt, openSampleSilenceOpt, openSampleFilterOpt, openSampleXFadeOpt;
 
   // mixer
   // 0xxx: output

src/gui/guiConst.cpp

@@ -743,6 +743,7 @@ const FurnaceGUIActionDef guiActions[GUI_ACTION_MAX]={
   D("SAMPLE_INVERT", "Invert", FURKMOD_CMD|FURKMOD_SHIFT|SDLK_t),
   D("SAMPLE_SIGN", "Signed/unsigned exchange", FURKMOD_CMD|SDLK_u),
   D("SAMPLE_FILTER", "Apply filter", FURKMOD_CMD|SDLK_f),
+  D("SAMPLE_XFADE_LOOP", "Crossfade loop points", NOT_AN_ACTION),
   D("SAMPLE_PREVIEW", "Preview sample", 0),
   D("SAMPLE_STOP_PREVIEW", "Stop sample preview", 0),
   D("SAMPLE_ZOOM_IN", "Zoom in", FURKMOD_CMD|SDLK_EQUALS),

src/gui/sampleEdit.cpp

@@ -1226,6 +1226,63 @@ void FurnaceGUI::drawSampleEdit() {
       ImGui::SameLine();
       ImGui::Dummy(ImVec2(4.0*dpiScale,dpiScale));
       sameLineMaybe();
+      ImGui::Button("Crossfade");
+      if (ImGui::IsItemHovered()) {
+        ImGui::SetTooltip("Crossfade loop points.");
+      }
+      if (openSampleXFadeOpt) {
+        openSampleXFadeOpt=false;
+        ImGui::OpenPopup("SXFadeOpt");
+      }
+      if (ImGui::BeginPopupContextItem("SXFadeÓpt",ImGuiPopupFlags_MouseButtonLeft)) {
+        if (ImGui::SliderInt("Number of samples", &sampleXFadeLoopLength, 0, 100000)) {
+          if (sampleXFadeLoopLength<0) sampleXFadeLoopLength=0;
+          if (sampleXFadeLoopLength>sample->loopStart) sampleXFadeLoopLength=sample->loopStart;
+          if (sampleXFadeLoopLength>100000) sampleXFadeLoopLength=100000;
+        }
+        if (ImGui::SliderInt("Linear <-> Equal power", &sampleXFadeLoopLaw, 0, 100000)) {
+          if (sampleXFadeLoopLaw<0) sampleXFadeLoopLaw=0;
+          if (sampleXFadeLoopLaw>100000) sampleXFadeLoopLaw=100000;
+        }
+        if (ImGui::Button("Apply")) {
+          sample->prepareUndo(true);
+          e->lockEngine([this,sample]{
+            SAMPLE_OP_BEGIN;
+            double l=1.0/(double)sampleXFadeLoopLength;
+            double evar=1.0-sampleXFadeLoopLaw/200000.0;
+            if (sample->depth==DIV_SAMPLE_DEPTH_8BIT) {
+              unsigned int xfadeInput=sample->loopStart-sampleXFadeLoopLength;
+              unsigned int xfadeOutput=sample->loopEnd-sampleXFadeLoopLength;
+              for (int i=0;i<sampleXFadeLoopLength;i++) {
+                double f1=std::pow(i*l,evar);
+                double f2=std::pow((sampleXFadeLoopLength-i)*l, evar);
+                signed char out=(signed char)(((double)sample->data8[xfadeInput])*f1+((double)sample->data8[xfadeOutput])*f2);
+                sample->data8[xfadeOutput]=out;
+                xfadeInput++;
+                xfadeOutput++;
+              }
+            } else if (sample->depth==DIV_SAMPLE_DEPTH_16BIT) {
+              unsigned int xfadeInput=sample->loopStart-sampleXFadeLoopLength;
+              unsigned int xfadeOutput=sample->loopEnd-sampleXFadeLoopLength;
+              for (int i=0;i<sampleXFadeLoopLength;i++) {
+                double f1=std::pow(i*l,evar);
+                double f2=std::pow((sampleXFadeLoopLength-i)*l,evar);
+                short out = (short)(((double)sample->data16[xfadeInput])*f1+((double)sample->data16[xfadeOutput])*f2);
+                sample->data16[xfadeOutput]=out;
+                xfadeInput++;
+                xfadeOutput++;
+              }
+            }
+            updateSampleTex=true;
+
+            e->renderSamples(curSample);
+          });
+          MARK_MODIFIED;
+          ImGui::CloseCurrentPopup();
+        }
+        ImGui::EndPopup();
+      }
+      ImGui::SameLine();
       if (ImGui::Button(ICON_FA_PLAY "##PreviewSample")) {
         e->previewSample(curSample);
       }