Sprite rotation

enriverd

Hi guys,

I need to render a Sprite rotated 90 degrees to the left, however if I call the roate function before drawing the sprite all my world gets rotated. I've tried calling pushMatrix and popMatrix before and after calling rotate and drawing the sprite but I see no difference.

Do you know how to achieve this??

Thanks in advance!

Simeon

function draw()
    background(40, 40, 50)

    -- Position of our sprite
    spritePos = vec2( WIDTH/2, HEIGHT/2 )

    -- Do this in a push/pop matrix block    
    pushMatrix()
    
    -- Translate to the position first
    translate(spritePos.x, spritePos.y)

    -- Then rotate
    rotate(90)

    -- Draw
    sprite("Tyrian Remastered:Boss D", 0, 0)
    
    popMatrix()
 
end

The reason you need to translate before rotating is due to the order of matrix operations.

It's a little bit unintuitive but you have to imagine the operations happening in the reverse order you set them — it's as if it rotates around the origin by 90 degrees, then translates to the sprite position (so it appears as if the sprite has rotated around its center at spritePos).

enriverd

Understand! I need to make my sprite position the center of the world first and then rotate the world before drawing my sprite to finally restore the previous wolrd matrix with a popMatrix! Makes sense! Thank you so much for the help!!

Bri_G

Hi enriverd,

Simeons covered the ground work - I'm still struggling here myself - as Simeon says this is a little unintuitive. There is a good example using mesh() in Codea - the one with the spinning gem pattern. It also includes a roptated shaded triangle fill and really demonstrates the power of the pad and Codea.

I'll post something later when I get my system running.

Bri_G

:)

Cabernet

And what about moving object? I have about 100 mooving sprites and each I need rotate. Is this posible or not?

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