From 1f2b1cb037a202cafe25167c071a2615341dafdb Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Sun, 24 Feb 2019 14:07:16 +0100
Subject: Further abstract mouse handling

---
 src/main.cc                   | 42 ++++++++++++++++++++---------------
 src/shader/code/interact.glsl | 51 +++++++++++++++++++------------------------
 2 files changed, 47 insertions(+), 46 deletions(-)

diff --git a/src/main.cc b/src/main.cc
index aa2456e..99e9a73 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -108,13 +108,17 @@ int renderWindow() {
 
 	auto pause_key = window.getKeyWatcher(GLFW_KEY_SPACE);
 
+	int prevMouseState = 0;
+	float prevLatticeMouseX;
+	float prevLatticeMouseY;
+
+	int currMouseState = 0;
+	float currLatticeMouseX;
+	float currLatticeMouseY;
+
 	auto tick_buffers = { lattice_a->getBuffer(), lattice_b->getBuffer(), fluid->getBuffer() };
 	auto tock_buffers = { lattice_b->getBuffer(), lattice_a->getBuffer(), fluid->getBuffer() };
 
-	int prevLatticeMouseState = 0;
-	int prevLatticeMouseX = 0;
-	int prevLatticeMouseY = 0;
-
 	window.render([&](bool window_size_changed) {
 		if ( pause_key.wasClicked() ) {
 			update_lattice = !update_lattice;
@@ -139,24 +143,28 @@ int renderWindow() {
 					tick = true;
 				}
 
-				/// Handle mouse-based interaction
-				const auto m = window.getMouse();
+				/// Update mouse projection
+				{
+					const auto m = window.getMouse();
 
-				if ( std::get<0>(m) != 0 || prevLatticeMouseState != 0 ) {
-					auto guard = interact_shader->use();
+					prevMouseState = currMouseState;
+					prevLatticeMouseX = currLatticeMouseX;
+					prevLatticeMouseY = currLatticeMouseY;
 
-					interact_shader->setUniform("prevMouseState", prevLatticeMouseState);
-					interact_shader->setUniform("prevMousePos", prevLatticeMouseX, prevLatticeMouseY);
+					currMouseState = std::get<0>(m);
+					currLatticeMouseX = float(std::get<1>(m)) / window.getWidth()  * world_width  + nX/2;
+					currLatticeMouseY = float(std::get<2>(m)) / window.getHeight() * world_height + nY/2;
+				}
 
-					const float latticeMouseX = float(std::get<1>(m)) / window.getWidth()  * world_width  + nX/2;
-					const float latticeMouseY = float(std::get<2>(m)) / window.getHeight() * world_height + nY/2;
+				/// Handle mouse-based interaction
+				if ( currMouseState != 0 || prevMouseState != 0 ) {
+					auto guard = interact_shader->use();
 
-					interact_shader->setUniform("currMouseState", std::get<0>(m));
-					interact_shader->setUniform("currMousePos", latticeMouseX, latticeMouseY);
+					interact_shader->setUniform("influxRequested", currMouseState == 1);
+					interact_shader->setUniform("wallRequested",   currMouseState == 2);
 
-					prevLatticeMouseState = std::get<0>(m);
-					prevLatticeMouseX = latticeMouseX;
-					prevLatticeMouseY = latticeMouseY;
+					interact_shader->setUniform("startOfLine", prevLatticeMouseX, prevLatticeMouseY);
+					interact_shader->setUniform("endOfLine", currLatticeMouseX, currLatticeMouseY);
 
 					interact_shader->dispatch(nX, nY);
 				}
diff --git a/src/shader/code/interact.glsl b/src/shader/code/interact.glsl
index a65d96a..cb69333 100644
--- a/src/shader/code/interact.glsl
+++ b/src/shader/code/interact.glsl
@@ -10,10 +10,11 @@ uniform uint nY;
 
 /// External influence
 
-uniform int  prevMouseState;
-uniform vec2 prevMousePos;
-uniform int  currMouseState;
-uniform vec2 currMousePos;
+uniform bool influxRequested;
+uniform bool wallRequested;
+
+uniform vec2 startOfLine;
+uniform vec2 endOfLine;
 
 /// Vector utilities
 
@@ -37,6 +38,14 @@ float distanceToLineSegment(vec2 a, vec2 b, vec2 p) {
 	return norm(pa - ab * (dot(ab, pa) / dot(ab, ab)));
 }
 
+bool isNearLine(uint x, uint y, float eps) {
+	if ( startOfLine == endOfLine ) {
+		return norm(vec2(x,y) - endOfLine) < eps;
+	} else {
+		return distanceToLineSegment(startOfLine, endOfLine, vec2(x,y)) < eps;
+	}
+}
+
 /// Array indexing
 
 uint indexOfFluidVertex(uint x, uint y) {
@@ -74,24 +83,6 @@ void disableWallInterior(uint x, uint y) {
 	}
 }
 
-/// Determine external influence
-
-bool isNearMouse(uint x, uint y, float eps) {
-	if ( prevMouseState == currMouseState ) {
-		return distanceToLineSegment(prevMousePos, currMousePos, vec2(x,y)) < eps;
-	} else {
-		return norm(vec2(x,y) - currMousePos) < eps;
-	}
-}
-
-bool isInfluxRequestedAt(uint x, uint y) {
-	return currMouseState == 1 && isNearMouse(x, y, 3);
-}
-
-bool isWallRequestedAt(uint x, uint y) {
-	return currMouseState == 2 && isNearMouse(x, y, 3);
-}
-
 /// Actual interaction kernel
 
 void main() {
@@ -105,13 +96,15 @@ void main() {
 	const int material = getMaterial(x,y);
 
 	if ( material == 1 ) {
-		if ( isInfluxRequestedAt(x,y) ) {
-			setMaterial(x,y,4);
-			return;
-		}
-		if ( isWallRequestedAt(x,y) ) {
-			setMaterial(x,y,3);
-			return;
+		if ( isNearLine(x, y, 3) ) {
+			if ( influxRequested ) {
+				setMaterial(x,y,4);
+				return;
+			}
+			if ( wallRequested ) {
+				setMaterial(x,y,3);
+				return;
+			}
 		}
 	}
 
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