scaling operates on matrix instead of vertices, new demo

README.md

@@ -19,26 +19,27 @@ Add the `g3d` subfolder folder to your project, and require it in `main.lua`.
 
 ## Usage
 
-The entire `main.lua` file for the demo shown is 30 lines, as shown here:
+The entire `main.lua` file for the demo shown is under 30 lines, as shown here:
 ```lua
 -- written by groverbuger for g3d
--- august 2020
+-- october 2020
 -- MIT license
 
 require "g3d"
 
 function love.load()
     Earth = Model:new("assets/sphere.obj", "assets/earth.png", {0,0,4}, nil, {-1,1,1})
     Moon = Model:new("assets/sphere.obj", "assets/moon.png", {5,0,4}, nil, {-0.5,0.5,0.5})
-    Background = Model:new("assets/soccerball.obj", "assets/skybox.png", {0,0,0}, nil, {500,500,500})
+    Background = Model:new("assets/sphere.obj", "assets/starfield.png", {0,0,0}, nil, {500,500,500})
+    Timer = 0
 end
 
 function love.mousemoved(x,y, dx,dy)
     FirstPersonCameraLook(dx,dy)
 end
 
 function love.update(dt)
-    Timer = Timer and Timer + dt or 0
+    Timer = Timer + dt
     Moon:setTranslation(math.cos(Timer)*5, 0, math.sin(Timer)*5 +4)
     Moon:setRotation(0,-1*Timer,0)
     FirstPersonCameraMovement(dt)
@@ -47,9 +48,7 @@ end
 function love.draw()
     Earth:draw()
     Moon:draw()
-    love.graphics.setWireframe(true)
     Background:draw()
-    love.graphics.setWireframe(false)
 end
 ```
 

g3d/matrices.lua

@@ -10,7 +10,7 @@
 
 -- returns a transformation matrix
 -- translation and rotation are 3d vectors
-function GetTransformationMatrix(translation, rotation)
+function GetTransformationMatrix(translation, rotation, scale)
     local ret = IdentityMatrix()
 
     -- translations
@@ -43,6 +43,13 @@ function GetTransformationMatrix(translation, rotation)
     rz[6] = math.cos(rotation[3])
     ret = MatrixMult(ret, rz)
 
+    -- scale
+    local sm = IdentityMatrix()
+    sm[1] = scale[1]
+    sm[6] = scale[2]
+    sm[11] = scale[3]
+    ret = MatrixMult(ret, sm)
+
     return ret
 end
 

g3d/model.lua

@@ -45,12 +45,7 @@ function Model:new(given, texture, translation, rotation, scale)
     self.texture = texture
     self.mesh = love.graphics.newMesh(self.vertexFormat, self.verts, "triangles")
     self.mesh:setTexture(self.texture)
-    self:setTransform(translation or {0,0,0}, rotation or {0,0,0})
-
-    -- if a scale was given, resize the model to the given scale
-    if scale then
-        self:scale(scale)
-    end
+    self:setTransform(translation or {0,0,0}, rotation or {0,0,0}, scale or {1,1,1})
 
     return self
 end
@@ -79,34 +74,35 @@ function Model:makeNormals()
     end
 end
 
--- resize model based on a given 3d vector
-function Model:scale(scaleVector)
-    for i,v in pairs(self.verts) do
-        v[1] = v[1] * scaleVector[1]
-        v[2] = v[2] * scaleVector[2]
-        v[3] = v[3] * scaleVector[3]
-    end
-    self.mesh = love.graphics.newMesh(self.vertexFormat, self.verts, "triangles")
-    self.mesh:setTexture(self.texture)
-end
-
 -- move and rotate given two 3d vectors
-function Model:setTransform(translation, rotation)
+function Model:setTransform(translation, rotation, scale)
     self.translation = translation or {0,0,0}
     self.rotation = rotation or {0,0,0}
-    self.matrix = GetTransformationMatrix(self.translation, self.rotation)
+    self.scale = scale or {1,1,1}
+    self:updateMatrix()
 end
 
 -- move given one 3d vector
 function Model:setTranslation(tx,ty,tz)
     self.translation = {tx,ty,tz}
-    self.matrix = GetTransformationMatrix(self.translation, self.rotation)
+    self:updateMatrix()
 end
 
 -- rotate given one 3d vector
 function Model:setRotation(rx,ry,rz)
     self.rotation = {rx,ry,rz}
-    self.matrix = GetTransformationMatrix(self.translation, self.rotation)
+    self:updateMatrix()
+end
+
+-- resize model's matrix based on a given 3d vector
+function Model:setScale(sx,sy,sz)
+    self.scale = {sx,sy,sz}
+    self:updateMatrix()
+end
+
+-- update the model's transformation matrix
+function Model:updateMatrix()
+    self.matrix = GetTransformationMatrix(self.translation, self.rotation, self.scale)
 end
 
 -- draw the model

main.lua

@@ -1,21 +1,22 @@
 -- written by groverbuger for g3d
--- august 2020
+-- october 2020
 -- MIT license
 
 require "g3d"
 
 function love.load()
     Earth = Model:new("assets/sphere.obj", "assets/earth.png", {0,0,4}, nil, {-1,1,1})
     Moon = Model:new("assets/sphere.obj", "assets/moon.png", {5,0,4}, nil, {-0.5,0.5,0.5})
-    Background = Model:new("assets/soccerball.obj", "assets/skybox.png", {0,0,0}, nil, {500,500,500})
+    Background = Model:new("assets/sphere.obj", "assets/starfield.png", {0,0,0}, nil, {500,500,500})
+    Timer = 0
 end
 
 function love.mousemoved(x,y, dx,dy)
     FirstPersonCameraLook(dx,dy)
 end
 
 function love.update(dt)
-    Timer = Timer and Timer + dt or 0
+    Timer = Timer + dt
     Moon:setTranslation(math.cos(Timer)*5, 0, math.sin(Timer)*5 +4)
     Moon:setRotation(0,-1*Timer,0)
     FirstPersonCameraMovement(dt)
@@ -24,7 +25,5 @@ end
 function love.draw()
     Earth:draw()
     Moon:draw()
-    love.graphics.setWireframe(true)
     Background:draw()
-    love.graphics.setWireframe(false)
 end