Fix selection on high-DPI/retina displays

Author: ruberith

GUI/OpenGL/MiniGL.cpp

@@ -34,6 +34,9 @@ MiniGL::DestroyFct MiniGL::destroyfunc = nullptr;
 void (*MiniGL::exitfunc)(void) = NULL;
 int MiniGL::m_width = 0;
 int MiniGL::m_height = 0;
+int MiniGL::m_windowWidth = 0;
+int MiniGL::m_windowHeight = 0;
+Real MiniGL::m_devicePixelRatio = 1.0f;
 Quaternionr MiniGL::m_rotation;
 Real MiniGL::m_zoom = 1.0;
 Vector3r MiniGL::m_translation;
@@ -686,7 +689,9 @@ void MiniGL::viewport ()
 {
 	glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
-	glfwGetFramebufferSize(m_glfw_window, &m_width, &m_height);
+    glfwGetFramebufferSize(m_glfw_window, &m_width, &m_height);
+    getWindowSize(m_windowWidth, m_windowHeight);
+    m_devicePixelRatio = static_cast<Real>(m_width) / static_cast<Real>(m_windowWidth);
 	glViewport (0, 0, m_width, m_height);
 	setProjectionMatrix (m_width, m_height);
 
@@ -787,8 +792,8 @@ void MiniGL::enableScreenShader(const Vector3r& color)
 {
     Shader& shader = m_shader_screen;
     shader.begin();
-    glUniform1f(shader.getUniform("width"), static_cast<Real>(m_width));
-    glUniform1f(shader.getUniform("height"), static_cast<Real>(m_height));
+    glUniform1f(shader.getUniform("width"), static_cast<Real>(m_windowWidth));
+    glUniform1f(shader.getUniform("height"), static_cast<Real>(m_windowHeight));
     glUniform3fv(shader.getUniform("color"), 1, &color(0));
 }
 
@@ -956,7 +961,11 @@ void MiniGL::unproject(const int x, const int y, Vector3r &pos)
 	glGetIntegerv(GL_VIEWPORT, viewport);
 
 	unproject(
-		Vector3r(static_cast<Real>(x), static_cast<Real>(viewport[3] - y), static_cast<Real>(znear)),
+        Vector3r(
+            static_cast<Real>(x) * m_devicePixelRatio,
+            static_cast<Real>(viewport[3]) - static_cast<Real>(y) * m_devicePixelRatio,
+            static_cast<Real>(znear)
+        ),
 		pos
 	);
 }

GUI/OpenGL/MiniGL.h

@@ -80,6 +80,9 @@ namespace SPH
 		static std::vector<MouseWheelFct> m_mouseWheelFct;
 		static int m_width;
 		static int m_height;
+        static int m_windowWidth;
+        static int m_windowHeight;
+        static Real m_devicePixelRatio;
 		static Vector3r m_translation;
 		static Quaternionr m_rotation;
 		static Real m_zoom;
@@ -199,6 +202,7 @@ namespace SPH
 
 		static int getWidth() { return m_width; }
 		static int getHeight() { return m_height; }
+        static Real getDevicePixelRatio() { return m_devicePixelRatio; }
 
 		static int getDrawMode() { return drawMode; }
 		static void setDrawMode(int val) { drawMode = val; }

GUI/OpenGL/Selection.h

@@ -42,10 +42,10 @@ namespace SPH
 			int itop = ip1y > ip2y ? ip1y : ip2y;
 			int ibottom = ip1y < ip2y ? ip1y : ip2y;
 
-			float left = (float)ileft;
-			float right = (float)iright;
-			float top = (float)itop;
-			float bottom = (float)ibottom;
+			float left = (float)ileft * MiniGL::getDevicePixelRatio();
+			float right = (float)iright * MiniGL::getDevicePixelRatio();
+			float top = (float)itop * MiniGL::getDevicePixelRatio();
+			float bottom = (float)ibottom * MiniGL::getDevicePixelRatio();
 
 			if (left != right && top != bottom)
 			{