3D interactive

Gamalex · April 21, 2024, 3:47pm

Hey everyone! I have problem with converting screen point to world position.
What is given: there are two 3D models on the left and on the right.
What I want: I click on the left model and it disappears.
What solution I see: convert the mouse coordinate into world coordinates and shoot the ray into depth, the first intersected object with a collision shape will be necessary.
What troubles I have: I used the script from the example for transforming coordinates, but the output is small numbers and the point is always approximately in the center. (Screen to World)
After experiments, I realized that if I give the camera an orthographic projection, the points become more or less plausible. Objects are selected incorrectly if they are nearby, but if you click in an empty area, nothing happens. In perspective projection it was selected even if you clicked on an empty space.
What could be the solution to this problem? How can you correctly determine which item you clicked on? Important point! You can click the mouse anywhere on the screen, not the center. And I would like a perspective projection.

selimanac · April 21, 2024, 5:30pm

github.com

rgrams/rendercam/blob/39df2361f1daaf15c8363fa51dfd83e03d34bad7/rendercam/rendercam.lua#L376

    
      
          
          
	local t = ( worldz - curCam.abs_nearZ) / (curCam.abs_farZ - curCam.abs_nearZ) -- normalize desired Z to 0-1 from abs_nearZ to abs_farZ
          	local worldpos = vmath.lerp(t, np, fp)
          
          
	if raw then return worldpos.x, worldpos.y, worldpos.z
          	else return vmath.vector3(worldpos.x, worldpos.y, worldpos.z) end -- convert vector4 to vector3
          end
          
          
-- Returns start and end points for a ray from the camera through the supplied screen coordinates
          -- Start point is on the camera near plane, end point is on the far plane.
          function M.screen_to_world_ray(x, y, raw)
          	if curCam.fixedAspectRatio then -- convert screen coordinates to viewport coordinates
          		x, y = M.screen_to_viewport(x, y)
          	end
          
          
	local m = vmath.inv(M.proj * M.view)
          
          
	-- Remap coordinates to range -1 to 1
          	local x1 = (x - M.window.x * 0.5) / M.window.x * 2
          	local y1 = (y - M.window.y * 0.5) / M.window.y * 2

Gamalex · April 21, 2024, 6:54pm

Thank you! This solution helped me.