Added love.touch.getPressure(touchid). Not useful on most touch-capable devices, but I do expect Apple's Force Touch to make it into iPhones in the near future.

src/modules/event/sdl/Event.cpp

@@ -277,6 +277,7 @@ Message *Event::convert(const SDL_Event &e) const
 		touchinfo.y = e.tfinger.y;
 		touchinfo.dx = e.tfinger.dx;
 		touchinfo.dy = e.tfinger.dy;
+		touchinfo.pressure = e.tfinger.pressure;
 
 #ifdef LOVE_LINUX
 		// FIXME: hacky workaround for SDL not normalizing touch coordinates in
@@ -310,6 +311,7 @@ Message *Event::convert(const SDL_Event &e) const
 		vargs.push_back(new Variant(touchinfo.y));
 		vargs.push_back(new Variant(touchinfo.dx));
 		vargs.push_back(new Variant(touchinfo.dy));
+		vargs.push_back(new Variant(touchinfo.pressure));
 
 		if (e.type == SDL_FINGERDOWN)
 			txt = "touchpressed";

src/modules/touch/Touch.h

@@ -46,6 +46,7 @@ public:
 		double y;  // Position in pixels along the y-axis.
 		double dx; // Amount in pixels moved along the x-axis.
 		double dy; // Amount in pixels moved along the y-axis.
+		double pressure;
 	};
 
 	virtual ~Touch() {}
@@ -63,6 +64,11 @@ public:
 	 **/
 	virtual void getPosition(int64 id, double &x, double &y) const = 0;
 
+	/**
+	 * Gets the pressure of a specific touch, using its ID.
+	 **/
+	virtual double getPressure(int64 id) const = 0;
+
 }; // Touch
 
 } // touch

src/modules/touch/sdl/Touch.cpp

@@ -51,6 +51,15 @@ void Touch::getPosition(int64 id, double &x, double &y) const
 	y = it->second.y;
 }
 
+double Touch::getPressure(int64 id) const
+{
+	const auto it = touches.find(id);
+	if (it == touches.end())
+		throw love::Exception("Invalid active touch ID: %d", id);
+
+	return it->second.pressure;
+}
+
 const char *Touch::getName() const
 {
 	return "love.touch.sdl";

src/modules/touch/sdl/Touch.h

@@ -43,11 +43,12 @@ public:
 
 	virtual ~Touch() {}
 
-	virtual std::vector<int64> getIDs() const;
-	virtual void getPosition(int64 id, double &x, double &y) const;
+	std::vector<int64> getIDs() const override;
+	void getPosition(int64 id, double &x, double &y) const override;
+	double getPressure(int64 id) const override;
 
 	// Implements Module.
-	virtual const char *getName() const;
+	const char *getName() const override;
 
 	// SDL has functions to query the state of touch presses, but unfortunately
 	// they are updated on a different thread in some backends, which causes

src/modules/touch/wrap_Touch.cpp

@@ -19,7 +19,6 @@
  **/
 
 #include "common/config.h"
-#include "common/int.h"
 
 // LOVE
 #include "wrap_Touch.h"
@@ -33,6 +32,14 @@ namespace touch
 
 #define instance() (Module::getInstance<Touch>(Module::M_TOUCH))
 
+int64 luax_checktouchid(lua_State *L, int idx)
+{
+	if (!lua_islightuserdata(L, idx))
+		return luax_typerror(L, idx, "touch id");
+
+	return (int64) (intptr_t) lua_touserdata(L, 1);
+}
+
 int w_getIDs(lua_State *L)
 {
 	std::vector<int64> ids = instance()->getIDs();
@@ -55,10 +62,7 @@ int w_getIDs(lua_State *L)
 
 int w_getPosition(lua_State *L)
 {
-	if (!lua_islightuserdata(L, 1))
-		return luax_typerror(L, 1, "touch id");
-
-	int64 id = (int64) (intptr_t) lua_touserdata(L, 1);
+	int64 id = luax_checktouchid(L, 1);
 
 	double x = 0;
 	double y = 0;
@@ -70,10 +74,20 @@ int w_getPosition(lua_State *L)
 	return 2;
 }
 
+int w_getPressure(lua_State *L)
+{
+	int64 id = luax_checktouchid(L, 1);
+	double pressure = 0.0;
+	luax_catchexcept(L, [&](){ pressure = instance()->getPressure(id); });
+	lua_pushnumber(L, pressure);
+	return 1;
+}
+
 static const luaL_Reg functions[] =
 {
 	{ "getIDs", w_getIDs },
 	{ "getPosition", w_getPosition },
+	{ "getPressure", w_getPressure },
 	{ 0, 0 }
 };
 

src/modules/touch/wrap_Touch.h

@@ -24,14 +24,17 @@
 // LOVE
 #include "Touch.h"
 #include "common/runtime.h"
+#include "common/int.h"
 
 namespace love
 {
 namespace touch
 {
 
+int64 luax_checktouchid(lua_State *L, int idx);
 int w_getIDs(lua_State *L);
 int w_getPosition(lua_State *L);
+int w_getPressure(lua_State *L);
 extern "C" LOVE_EXPORT int luaopen_love_touch(lua_State *L);
 
 } // touch