Added model preview while dragging model into viewport and outline fully opaque

Resources/Shaders/add.shader

@@ -0,0 +1,32 @@
+#shader vertex
+#version 440 core
+
+layout(location = 0) in vec3 VertexPosition;
+layout(location = 1) in vec2 UVPosition;
+
+out flat vec2 UV;
+
+void main()
+{
+    UV = UVPosition;
+    gl_Position = vec4(VertexPosition, 1.0f);
+}
+
+#shader fragment
+#version 440 core
+
+uniform sampler2D u_Source;
+uniform sampler2D u_Source2;
+
+in vec2 UV;
+
+out vec4 FragColor;
+
+void main()
+{
+    vec4 a = texture(u_Source, UV);
+    vec4 b = texture(u_Source2, UV);
+
+    float luminance = max(b.r, max(b.g, b.b));
+    FragColor = vec4(mix(a.rgb, b.rgb, luminance), a.a);
+}