# Lerp for matrix3 values

 09 September 2010 JHN maxscript/c# lover   Johan Boekhoven Technical Artist Freelance TD/Generalist Netherlands Lerp for matrix3 values Is there an existing way to lerp between 2 matrix values or do I have to decompose the PRS values, (s)lerp them and rebuilt the matrix each step? Thanks, -Johan __________________ Online: LinkedIn share quote
 09 September 2010 JHN maxscript/c# lover   Johan Boekhoven Technical Artist Freelance TD/Generalist Netherlands Found a thread about it : http://forums.cgsociety.org/showthr...p?f=98&t=859470 Thanks, -Johan __________________ Online: LinkedIn share quote
 09 September 2010 MatanH GameDev & TechArt   portfolio Matan Halberstadt Game Developer & Tech Artist OneHamsa Tel-Aviv, Israel Just saw your 2nd post but I'll post my solution anyhow.. ``````( fn lerp matArray weights = ( local resMat = matrix3 [0,0,0] [0,0,0] [0,0,0] [0,0,0] for i = 1 to matArray.count do ( local w = weights[i] local intMat = matrix3 [w,0,0] [0,w,0] [0,0,w] [w,w,w] resMat += matArray[i] * intMat ) resMat ) if selection.count == 3 then ( local a = \$[1] local b = \$[2] local c = \$[3] local d = copy a d.transform = lerp #(a.transform, b.transform, c.transform) #(0.5, 0.5, 0.5) ) else messageBox "Please select 3 objects!" )`````` __________________ Home: http://cargocollective.com/matan Work: https://onehamsa.com share quote
 09 September 2010 denisT MAX Doctor   portfolio Denis Trofimov CA, USA Originally Posted by JHN: Is there an existing way to lerp between 2 matrix values or do I have to decompose the PRS values, (s)lerp them and rebuilt the matrix each step? Thanks, -Johan there is no lerp for matrices. use lerp for rotation (in quaternions), and average for position and scale. share quote
 09 September 2010 JHN maxscript/c# lover   Johan Boekhoven Technical Artist Freelance TD/Generalist Netherlands @ Matan : Thanks, I'm using something else since I just need to blend between 2 matrices (making a pose tool for CAT). Will test you code as it looks more compact. @ Denis : I'm using a slightly modified variant on your code ``````fn blendMatrix m1: m2: weight:0.5 = ( fn dotQuat q q_prev = ( (q.w * q_prev.w + q.x * q_prev.x + q.y * q_prev.y + q.z * q_prev.z) < 0 ) r1 = m1.rotationpart r2 = m2.rotationpart if (dotQuat r1 r2) do r1 *=-1 r = slerp (normalize r1) (normalize r2) weight t = m1.translationpart + (m2.translationpart - m1.translationpart) * weight s = m1.scalepart + (m2.scalepart - m1.scalepart) * weight translate (rotate (scale (matrix3 1) s true) r) t -- ignores scale ) `````` I added the scale averaging, and encapsulated the dotQuat fn. Thanks! -Johan __________________ Online: LinkedIn share quote
 09 September 2010 JHN maxscript/c# lover   Johan Boekhoven Technical Artist Freelance TD/Generalist Netherlands @Matan, does it work between 2 transforms. I tried: `````` for i = 1 to 10 do point transform:(lerpM #(\$[1].transform, \$[2].transform) #((i/10.), (1 - (i/10))))`````` Between 2 objects that are transformed differently, but the results are not good. How does your function work with 2 matrices? Thanks, -Johan __________________ Online: LinkedIn share quote
 09 September 2010 MatanH GameDev & TechArt   portfolio Matan Halberstadt Game Developer & Tech Artist OneHamsa Tel-Aviv, Israel it won't work correct if the weights don't sum up to exactly 1.0 here is an example of what you tried to do: ``````local a = \$[1] local b = \$[2] local n = 10 for i = 1 to n - 1 do ( local c = copy a local w = 1.0 * i / n c.transform = lerp #(a.transform, b.transform) #(w, 1.0 - w) )`````` EDIT: just playing around with it, here is another nice test: ``````( fn lerp matArray weights = ( local resMat = matrix3 [0,0,0] [0,0,0] [0,0,0] [0,0,0] for i = 1 to matArray.count do ( local w = weights[i] local intMat = matrix3 [w,0,0] [0,w,0] [0,0,w] [w,w,w] resMat += matArray[i] * intMat ) resMat ) local a = teapot transform:(matrix3 [0.543478,1.19095,-0.738627] [-1.22502,0.788501,0.370005] [1.21654,0.836836,2.24443] [204.994,154.378,224.798]) wirecolor:red local b = teapot transform:(matrix3 [1,0,0] [0,1,0] [0,0,1] [122.507,3.13654,0]) wirecolor:green local c = teapot transform:(matrix3 [1.06301,0.5229,0.250736] [-0.301877,-0.31541,1.93761] [0.425891,-0.832628,-0.0691843] [288.803,-141.283,52.8861]) wirecolor:blue local n = 10 for j = 0 to n do ( local w1 = 1.0 * j / n for i = 0 to n do ( local d = copy a local w2 = (1.0 - w1) * i / n local w3 = 1.0 - w1 - w2 d.transform = lerp #(a.transform, b.transform, c.transform) #(w1, w2, w3) d.wireColor = a.wireColor * w1 + b.wireColor * w2 + c.wireColor * w3 ) ) )`````` __________________ Home: http://cargocollective.com/matan Work: https://onehamsa.com Last edited by MatanH : 09 September 2010 at 01:18 PM. share quote
 09 September 2010 JHN maxscript/c# lover   Johan Boekhoven Technical Artist Freelance TD/Generalist Netherlands I went wrong because my code produced an integer as weight instead of a float. But still your solution is not as good because the scale of the matrix is not avaraged, but get's distorted. So I'm sticking with my (Denis' actually) code. But there's some nice motion design effects to be made with your code! Thanks, -Johan __________________ Online: LinkedIn share quote
 09 September 2010 eek Fixer   portfolio Charles Looker Snr Technical Artist Electronic Arts Vancouver, Canada `````` local matrices = #((matrix3 1), ((eulerangles 0 45 32) as matrix3), (transMatrix [50,40,10])) local mc = for each in matrices collect each local tmp = #() local t = 0.5 while mc.count > 1 do ( for i = 1 to (mc.count-1) do ( append tmp ((slerp mc[i].rotation mc[i+1].rotation t) as matrix3 * transMatrix((1-t) * mc[i].row4 + mc[i+1].row4 * t)) ) mc = tmp tmp = #() ) mc[1] `````` This is a quadratic form of blending between multiple matrices roughly. __________________ Disclaimer: My opinions are not those of my employer. share quote
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