How camera works?

britzl · July 30, 2019, 2:52pm

render.set_viewport(0,0,800,600) means that if you have a window that is for instance 1400x1200 pixels then the game will render only in the area from 0x0 to 800x600. The rest will not be used when rendering.

What is actually being rendered in those 800x600 pixels depends on the view and projection that you use. You need to position your camera accordingly and you need to make sure to use a suitable projection.

Vik · July 30, 2019, 3:04pm

The capture that I upload show it. The same camera position, I resize the window, and it show more game area , that is not the objective.

britzl · July 30, 2019, 3:28pm

Here’s a complete example:

I’m basing this off the default.render_script with the required modifications to be able to crop using black bars when using fixed_fit_projection.

Enable crop like this:

msg.post("@render:", "use_fixed_fit_projection", { near = -1, far = 1, crop = true })

And this is the render script:

github.com

britzl/publicexamples/blob/master/examples/crop_viewport/main/crop.render_script#L18-L60


--
-- projection that centers and fits content with maintained aspect ratio
-- optionally cropping left/right or top/bottom
--
local function fixed_fit_projection(self)
    local width = render.get_width()
    local height = render.get_height()
    local window_width = render.get_window_width()
    local window_height = render.get_window_height()
    local width_ratio = window_width / width
    local height_ratio = window_height / height
    local zoom = math.min(width_ratio, height_ratio)


    -- if no cropping should take place then the "fixed fit projection" is the same as
    -- using a "fixed projection" with a dynamic zoom
    if not self.camera_settings.crop then
        self.camera_settings.zoom = zoom
        fixed_projection(self)
        return
    end

This file has been truncated. show original

Vik · July 30, 2019, 6:33pm

I think now is working as expected, but have no zoom.

britzl · July 30, 2019, 6:37pm

Well, you mentioned fixed fit which adjusts the zoom automatically.

Vik · July 30, 2019, 6:51pm

and cannot use zoom some way in this mode?

britzl · July 30, 2019, 6:53pm

As I said, the zoom is automatically calculated here:

github.com

britzl/publicexamples/blob/master/examples/crop_viewport/main/crop.render_script#L29


-- projection that centers and fits content with maintained aspect ratio
-- optionally cropping left/right or top/bottom
--
local function fixed_fit_projection(self)
    local width = render.get_width()
    local height = render.get_height()
    local window_width = render.get_window_width()
    local window_height = render.get_window_height()
    local width_ratio = window_width / width
    local height_ratio = window_height / height
    local zoom = math.min(width_ratio, height_ratio)


    -- if no cropping should take place then the "fixed fit projection" is the same as
    -- using a "fixed projection" with a dynamic zoom
    if not self.camera_settings.crop then
        self.camera_settings.zoom = zoom
        fixed_projection(self)
        return
    end


    local aspect_ratio = width / height

Modify the script and provide your own zoom.

Vik · July 30, 2019, 7:16pm

thanks

misterduke · March 14, 2021, 1:59pm

I’m going through old threads in search of an answer for a similar problem, and I’m also feeling frustrated. Rendercam and Orthographic Camera are the recommended solutions, and I’m sure they work for what they’re intended for, but I couldn’t get them working for my situation.

Because I’ve hit a brick wall with this, I’ve decided to hire someone more experienced to help. It would have been nice to solve the problem myself, but the tutorials and information are too complicated for me.

The videos and posts here on the forum often suggest how simple and easy it is to understand and implement, but I wish that was the case. For someone who isn’t a computer science major or proficient at advanced math, the topics (e.g., formulas, inverting matrices, rendering, etc.) are very difficult.

misterduke · March 14, 2021, 2:21pm

britzl:

This is the trickiest part and something that the current camera doesn’t support. You need to keep track of the projection and translate mouse positions on your own. We will never automatically translate coordinates for you in say on_input() but maybe we could potentially provide something like:

Yes, this would be very helpful. It’s the one thing preventing me from having the functionality I want with my game.