drawable shapes

[tiotags]

Hello,

An idea for the next version of love, make the shapes (polygon, circle) drawables, so you can draw them with love.graphics.draw

an example:

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specialtriangle = love.graphics.newWhatever(x1,y1,x2,y2,x3,y3)
love.graphics.draw(specialtriangle,whatever,whatever)

Any opinions ?

[Robin]

That might be an idea, but I don't think it should be in the LÖVE core: Shapes are for physics simulation, not for drawing (you have Images for that ). However, you (or someone else) could write a function that draws Shapes in the right position with primitives, maybe to be used together with CAMERA?

[kikito]

With polygon & rectangle shapes it is very straightforward to do:

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triangle = love.physics.newPolygonShape(body, 100,200, 200,100, 300, 200)
square = love.physics.newRectangleShape(body, 100,400, 100,100)
...
love.graphics.polygon( 'line', triangle:getPoints() )
love.graphics.polygon( 'line', square:getPoints() )

Circle shapes are a bit more difficult. The CircleShape api includes a (undocummented) method called getRadius, but not a getLocalPosition (I created a tracker item for this some weeks ago). So you have to cover that by using getBoundingBox:

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circle = love.physics.newCircleChape(body, 100,500, 50)
...
local x1, y1, x2, y2, x3, y3, x4, y4 = circle:getBoundingBox( )
local xMin, yMin, xMax = math.min(x1,x2,x3,x4), math.min(y1,y2,y3,y4), math.max(x1,x2,x3,x4)
local radius = (xMax-xMin)/2
love.graphics.circle( 'line', xMin+radius, yMin+radius, radius, radius*3) --last parameter ensures that the circle looks pretty no matter what

So I suppose you could bind all this together in one nice function. The trick is differentiating between polygonal/rectangular and circled shapes. Fortunately, we know that circled shapes don't have a getPoints function. So we test for that, and invoke one or the other method, like this:

Code: Select all

function drawShape(shape, style)
  assert(type(shape.getBody)=='function', "draw shape needs a shape as its first parameter")
  style = style or 'line' --style is 'line' by default
  if(type(shape.getPoints)=='function') -- it has a getPoints function, so it is a polygon/rectangle shape
    love.graphics.polygon( 'line', square:getPoints() )
  else -- it must be a circled shape then
    local x1, y1, x2, y2, x3, y3, x4, y4 = shape:getBoundingBox( )
    local xMin, yMin, xMax = math.min(x1,x2,x3,x4), math.min(y1,y2,y3,y4), math.max(x1,x2,x3,x4)
    local radius = (xMax-xMin)/2
    love.graphics.circle( 'line', xMin+radius, yMin+radius, radius, radius*3)
  end
end

DISCLAIMER: I wrote this function from the top of my head and haven't tested it. Some bug might have slipped through. Please comment if that is the case.

[osuf oboys]

Seems reasonable since this de facto is what we're doing during debug anyhow.

kikito: You can also use shape:getType() to get rid of the function testing. This could also be used to make a seamless extension of the love.graphics.draw function, checking if what we send is a shape or not.

[kikito]

Heh, I didn't see that one! Indeed, the getType() function is the way to go.