5 files changed, 34 insertions, 5 deletions
diff --git a/engines/sci/engine/kgraphics.cpp b/engines/sci/engine/kgraphics.cpp
index c60c0a44b9..ce670b21fe 100644
--- a/engines/sci/engine/kgraphics.cpp
+++ b/engines/sci/engine/kgraphics.cpp
@@ -1471,10 +1471,8 @@ reg_t kSetShowStyle(EngineState *s, int argc, reg_t *argv) {
 }
 
 reg_t kCelInfo(EngineState *s, int argc, reg_t *argv) {
-	// TODO: This is all a stub/skeleton, thus we're invoking kStub() for now
-	kStub(s, argc, argv);
-
-	// Used by Shivers 1, room 23601
+	// Used by Shivers 1, room 23601 to determine what blocks on the red door puzzle board
+	// are occupied by pieces already
 
 	// 6 arguments, all integers:
 	// argv[0] - subop (0 - 4). It's constantly called with 4 in Shivers 1
@@ -1490,7 +1488,21 @@ reg_t kCelInfo(EngineState *s, int argc, reg_t *argv) {
 	// 2, 3 - nop
 	// 4 - return value of pixel at x, y
 
-	return s->r_acc;
+	switch (argv[0].toUint16()) {
+		case 4: {
+			GuiResourceId viewId = argv[1].toSint16();
+			int16 loopNo = argv[2].toSint16();
+			int16 celNo = argv[3].toSint16();
+			int16 x = argv[4].toUint16();
+			int16 y = argv[5].toUint16();
+			byte color = g_sci->_gfxCache->kernelViewGetColorAtCoordinate(viewId, loopNo, celNo, x, y);
+			return make_reg(0, color);
+		}
+		default: {
+			kStub(s, argc, argv);
+			return s->r_acc;
+		}
+	}
 }
 
 reg_t kScrollWindow(EngineState *s, int argc, reg_t *argv) {
diff --git a/engines/sci/graphics/cache.cpp b/engines/sci/graphics/cache.cpp
index d2bd76ac99..55f8624c49 100644
--- a/engines/sci/graphics/cache.cpp
+++ b/engines/sci/graphics/cache.cpp
@@ -102,4 +102,8 @@ int16 GfxCache::kernelViewGetCelCount(GuiResourceId viewId, int16 loopNo) {
 	return getView(viewId)->getCelCount(loopNo);
 }
 
+byte GfxCache::kernelViewGetColorAtCoordinate(GuiResourceId viewId, int16 loopNo, int16 celNo, int16 x, int16 y) {
+	return getView(viewId)->getColorAtCoordinate(loopNo, celNo, x, y);
+}
+
 } // End of namespace Sci
diff --git a/engines/sci/graphics/cache.h b/engines/sci/graphics/cache.h
index c090cda7d7..2f462fe042 100644
--- a/engines/sci/graphics/cache.h
+++ b/engines/sci/graphics/cache.h
@@ -49,6 +49,8 @@ public:
 	int16 kernelViewGetLoopCount(GuiResourceId viewId);
 	int16 kernelViewGetCelCount(GuiResourceId viewId, int16 loopNo);
 
+	byte kernelViewGetColorAtCoordinate(GuiResourceId viewId, int16 loopNo, int16 celNo, int16 x, int16 y);
+
 private:
 	void purgeFontCache();
 	void purgeViewCache();
diff --git a/engines/sci/graphics/view.cpp b/engines/sci/graphics/view.cpp
index a0d5b51a2b..d5c52bfb59 100644
--- a/engines/sci/graphics/view.cpp
+++ b/engines/sci/graphics/view.cpp
@@ -837,4 +837,13 @@ void GfxView::adjustBackUpscaledCoordinates(int16 &y, int16 &x) {
 	_screen->adjustBackUpscaledCoordinates(y, x, _sci2ScaleRes);
 }
 
+byte GfxView::getColorAtCoordinate(int16 loopNo, int16 celNo, int16 x, int16 y) {
+	const CelInfo *celInfo = getCelInfo(loopNo, celNo);
+	const byte *bitmap = getBitmap(loopNo, celNo);
+	const int16 celWidth = celInfo->width;
+
+	bitmap += (celWidth * y);
+	return bitmap[x];
+}
+
 } // End of namespace Sci
diff --git a/engines/sci/graphics/view.h b/engines/sci/graphics/view.h
index 19ef2e62f8..d3473f1024 100644
--- a/engines/sci/graphics/view.h
+++ b/engines/sci/graphics/view.h
@@ -85,6 +85,8 @@ public:
 	void adjustToUpscaledCoordinates(int16 &y, int16 &x);
 	void adjustBackUpscaledCoordinates(int16 &y, int16 &x);
 
+	byte getColorAtCoordinate(int16 loopNo, int16 celNo, int16 x, int16 y);
+
 private:
 	void initData(GuiResourceId resourceId);
 	void unpackCel(int16 loopNo, int16 celNo, byte *outPtr, uint32 pixelCount);