noggit: world: fix cursor plane not visible underwater by rendering i…

…t before the water and making it write to the depth buffer, add checker board pattern to be able to see the water under it still

src/noggit/World.cpp

@@ -1474,6 +1474,53 @@ void World::draw ( math::matrix_4x4 const& model_view
   gl.enable(GL_BLEND);
   gl.blendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
+  // render before the water and enable depth right 
+  // so it's visible under water
+  // the checker board pattern is used to see the water under it
+  if (angled_mode || use_ref_pos)
+  {
+    opengl::scoped::depth_mask_setter<GL_TRUE> const depth_mask;
+
+    math::degrees orient = math::degrees(orientation);
+    math::degrees incl = math::degrees(angle);
+    math::vector_4d color = cursor_color;
+
+    color.w = 0.75f;
+
+    float radius = 1.2f * brush_radius;
+
+    if (angled_mode && !use_ref_pos)
+    {
+      math::vector_3d pos = cursor_pos;
+      pos.y += 0.1f; // to avoid z-fighting with the ground
+      _square_render.draw(mvp, pos, radius, incl, orient, color);
+    }
+    else if (use_ref_pos)
+    {
+      if (angled_mode)
+      {
+        math::vector_3d pos = cursor_pos;
+        pos.y = misc::angledHeight(ref_pos, pos, incl, orient);
+        pos.y += 0.1f;
+        _square_render.draw(mvp, pos, radius, incl, orient, color);
+
+        // display the plane when the cursor is far from ref_point
+        if (misc::dist(pos.x, pos.z, ref_pos.x, ref_pos.z) > 10.f + radius)
+        {
+          math::vector_3d ref = ref_pos;
+          ref.y += 0.1f;
+          _square_render.draw(mvp, ref, 10.f, incl, orient, color);
+        }
+      }
+      else
+      {
+        math::vector_3d pos = cursor_pos;
+        pos.y = ref_pos.y + 0.1f;
+        _square_render.draw(mvp, pos, radius, math::degrees(0.f), math::degrees(0.f), color);
+      }
+    }
+  }
+
   if (terrainMode == editing_mode::object && has_multiple_model_selected())
   {
     opengl::scoped::bool_setter<GL_DEPTH_TEST, GL_FALSE> const disable_depth_test;
@@ -1541,50 +1588,7 @@ void World::draw ( math::matrix_4x4 const& model_view
     gl.bindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
   }
 
-  if (angled_mode || use_ref_pos)
-  {
-    opengl::scoped::bool_setter<GL_CULL_FACE, GL_FALSE> cull;
-    opengl::scoped::depth_mask_setter<GL_FALSE> const depth_mask;
-
-    math::degrees orient = math::degrees(orientation);
-    math::degrees incl = math::degrees(angle);
-    math::vector_4d color = cursor_color;
-    // always half transparent regardless or the cursor transparency
-    color.w = 0.5f;
-
-    float radius = 1.2f * brush_radius;
-
-    if (angled_mode && !use_ref_pos)
-    {
-      math::vector_3d pos = cursor_pos;
-      pos.y += 0.1f; // to avoid z-fighting with the ground
-      _square_render.draw(mvp, pos, radius, incl, orient, color);
-    }
-    else if (use_ref_pos)
-    {
-      if (angled_mode)
-      {
-        math::vector_3d pos = cursor_pos;
-        pos.y = misc::angledHeight(ref_pos, pos, incl, orient);
-        pos.y += 0.1f;
-        _square_render.draw(mvp, pos, radius, incl, orient, color);
-
-        // display the plane when the cursor is far from ref_point
-        if (misc::dist(pos.x, pos.z, ref_pos.x, ref_pos.z) > 10.f + radius)
-        {
-          math::vector_3d ref = ref_pos;
-          ref.y += 0.1f;
-          _square_render.draw(mvp, ref, 10.f, incl, orient, color);
-        }
-      }
-      else
-      {
-        math::vector_3d pos = cursor_pos;
-        pos.y = ref_pos.y + 0.1f;
-        _square_render.draw(mvp, pos, radius, math::degrees(0.f), math::degrees(0.f), color);
-      }
-    }
-  }
+
 
   // draw last because of the transparency
   if (draw_mfbo)

src/opengl/primitives.cpp

@@ -159,6 +159,10 @@ out vec4 out_color;
 
 void main()
 {
+  if(gl_FragCoord.x < 0.5)
+  {
+    discard;
+  }
   out_color = color;
 }
 )code"
@@ -267,6 +271,8 @@ void main()
 
 in vec4 position;
 
+out vec3 f_pos;
+
 uniform mat4 model_view_projection;
 uniform vec3 origin;
 uniform float radius;
@@ -286,6 +292,8 @@ void main()
 
   pos.xyz += origin;
   gl_Position = model_view_projection * pos;
+
+  f_pos = position.xyz;
 }
 )code"
                    }
@@ -295,10 +303,21 @@ void main()
 
 uniform vec4 color;
 
+in vec3 f_pos;
+
 out vec4 out_color;
 
 void main()
 {
+  bool discard_x = mod((f_pos.x + 1.) * 5., 2.) < 1.;
+  bool discard_y = mod((f_pos.z + 1.) * 5., 2.) < 1.;
+
+  // discard in a checker board pattern
+  if(discard_x != discard_y)
+  {
+    discard;
+  }
+
   out_color = color;
 }
 )code"