Add often used built-ins (camera-pos, object-pos, camera-eye etc.) to spatial shaders

[paddy-exe]

Implements this proposal: godotengine/godot-proposals#4957

(Updated) Syntax of implementation for written shaders

vec3 node_pos_world = NODE_POSITION_WORLD;
vec3 camera_pos_world = CAMERA_POSITION_WORLD;
vec3 camera_dir_world = CAMERA_DIRECTION_WORLD;
vec3 node_pos_view = NODE_POSITION_VIEW;

(Updated) Showcase in visual shaders:

(Old syntax) Showcase in written shaders:

Node3D.tscn.-.Shader-Spatial-Built-Ins-Test.-.Godot.Engine.2022-07-29.13-54-16.mp4

[QbieShay]

Hey @paddy-exe , thank you so much for this!

[paddy-exe]

Hey @paddy-exe , thank you so much for this!

Sure! If you have any suggestion for other built-ins I can implement, let me know

[QbieShay]

Because the fragment is in view space, I think it could be useful to have those variables as well in view space

[paddy-exe]

Hmm yeah I agree but we have to be careful that we don't overload the input node with too many built-ins since the list is already quite long:

I will probably first wait for feedback from @clayjohn and @Chaosus since this is their field

[Chaosus]

Seems useful, especially for visual shaders.

[paddy-exe]

I updated the syntax naming to be in line with each other. I updated the syntax in the first comment as well
WORLD_CAMERA_EYE is now CAMERA_WORLD_EYE

[paddy-exe]

@QbieShay I added the ObjectViewPosition as a new input:

Node3D.tscn.-.Shader-Spatial-Built-Ins-Test.-.Godot.Engine.2022-07-30.17-06-42.mp4

[paddy-exe]

Autocompletion in the visual shader add-node dialog works now too

[William-Godwin]

Is it possible to add the same variables to the particle shader? This would be very handy for some effects. I think...

[paddy-exe]

After chatting on discord with @William-Godwin we decided it would be best to create a new proposal for his needs in particle shaders since they would require more in-depth changes and would complicate the status of this PR

[QbieShay]

Proposition to rename "ObjectViewPosition" and "ObjectWorldPosition" to "NodePositionView" and "NodePositionWorld"

Of note, all other engines work in either world or object space, we are the only one working in view space.

@clayjohn @Calinou @reduz opinions on the names?

[clayjohn]

Proposition to rename "ObjectViewPosition" and "ObjectWorldPosition" to "NodePositionView" and "NodePositionWorld"

Of note, all other engines work in either world or object space, we are the only one working in view space.

@clayjohn @Calinou @reduz opinions on the names?

I have no strong opinion on the naming. Object to me sounds more natural, but Node fits better with the naming we use outside of shaders so it is likely more approachable for users. I would go with Qbie's suggested names for now.

I am a little confused about CAMERA_WORLD_EYE The eye vector usually refers to the direction between a fragment/vertex and the camera. I expected this to return the direction between the object center and the Camera in world space, but of course that is not what this does. Can you clarify what it is CAMERA_WORLD_EYE is supposed to represent so we can figure out a more intuitive name?

[paddy-exe]

Okay so I updated the syntax according to @QbieShay 's feedback:

vec3 object_world_pos = NODE_POSITION_WORLD; // returns the object position in world space
vec3 camera_pos = CAMERA_POSITION_WORLD; // returns the camera position in world space
vec3 camera_world_eye = CAMERA_EYE_WORLD; // returns the camera eye vector in world space direction of the camera
vec3 object_view_pos = NODE_POSITION_VIEW; // returns the object position in view space

@clayjohn I actually just wanted to implement the same that I documented here for this godot-docs PR.
I would describe it as the camera view direction vector in world space
godotengine/godot-docs@e5f23ee#diff-3df75bc2fdd44e719dd72a78099844ccb88e1190d2fc3d432b75030590b0ae98R239

[akien-mga]

Approved in PR review meeting.

Last change requested would be to rename CAMERA_EYE_WORLD to CAMERA_DIRECTION_WORLD (proposed by @JFonS and approved by @QbieShay and @reduz).

[paddy-exe]

@akien-mga Thanks for the quick feedback! Rebased everything and updated to your feedback.
Also updated the PR document (in the beginning) for anyone reading this later on.

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉

[celyk]

Shouldn't that
actions.renames["CAMERA_DIRECTION_WORLD"] = "scene_data.view_matrix[3].xyz";
be using -scene_data.inv_view_matrix[2].xyz, as in the camera forward vector?
So actions.renames["CAMERA_DIRECTION_WORLD"] = "-scene_data.inv_view_matrix[2].xyz";

Also, I think this
actions.renames["NODE_POSITION_VIEW"] = "(model_matrix * scene_data.view_matrix)[3].xyz";
Should be this
actions.renames["NODE_POSITION_VIEW"] = "(scene_data.view_matrix * model_matrix[3]).xyz";