Graphics/AbstractViewer: Add Project/Unproject methods

src/Nazara/Graphics/AbstractViewer.cpp

@@ -3,6 +3,7 @@
 // For conditions of distribution and use, see copyright notice in Config.hpp
 
 #include <Nazara/Graphics/AbstractViewer.hpp>
+#include <Nazara/Renderer/RenderTarget.hpp>
 #include <Nazara/Graphics/Debug.hpp>
 
 namespace Nz
@@ -16,4 +17,39 @@ namespace Nz
 	*/
 
 	AbstractViewer::~AbstractViewer() = default;
+
+	Vector3f AbstractViewer::Project(const Nz::Vector3f& worldPosition) const
+	{
+		Vector4f pos4D(worldPosition, 1.f);
+		pos4D = GetViewMatrix() * pos4D;
+		pos4D = GetProjectionMatrix() * pos4D;
+		pos4D /= pos4D.w;
+
+		Rectf viewport = Rectf(GetViewport());
+
+		Nz::Vector3f screenPosition(pos4D.x * 0.5f + 0.5f, -pos4D.y * 0.5f + 0.5f, pos4D.z * 0.5f + 0.5f);
+		screenPosition.x = screenPosition.x * viewport.width + viewport.x;
+		screenPosition.y = screenPosition.y * viewport.height + viewport.y;
+
+		return screenPosition;
+	}
+
+	Vector3f AbstractViewer::Unproject(const Nz::Vector3f& screenPos) const
+	{
+		Rectf viewport = Rectf(GetViewport());
+
+		Nz::Vector4f normalizedPosition;
+		normalizedPosition.x = (screenPos.x - viewport.x) / viewport.width * 2.f - 1.f;
+		normalizedPosition.y = (screenPos.y - viewport.y) / viewport.height * 2.f - 1.f;
+		normalizedPosition.z = screenPos.z * 2.f - 1.f;
+		normalizedPosition.w = 1.f;
+
+		Nz::Matrix4f invMatrix = GetViewMatrix() * GetProjectionMatrix();
+		invMatrix.Inverse();
+
+		Nz::Vector4f worldPos = invMatrix * normalizedPosition;
+		worldPos /= worldPos.w;
+
+		return Nz::Vector3f(worldPos.x, worldPos.y, worldPos.z);
+	}
 }