Libs3D Mesh

Supported platforms:

I am 3D

First and foremost, for 3D, we set our application as such. There are many ways to tell our application be 3D:

• application configureFrustum
• Matrix orthographicProjection
• Matrix perspectiveProjection
• Viewport setProjection

Let's see some of those making our first steps in Gideros 3D.

Flat 3D

A Triangle

As seen above, first we set our application 3D: configureFrustum.

The Mesh class is used to create and display custom constructed triangles (triangle meshes).

A triangle is:

• an array of 3 vertices with an x and y position: setVertexArray
• those 3 vertices connect to make a face (ClockWise): setIndexArray
• optionally coloring each vertex (color and alpha): setColorArray

The code:

application:setBackgroundColor(0x323232)

-- Configures the field of view (fov) and far clipping plane for 3D projection
application:configureFrustum(45, -100) -- (fov, farplane)

local mesh = Mesh.new()

mesh:setVertexArray(
	50, 0, -- 1. vertex position
	100, 100, -- 2. vertex position
	0, 100 -- 3. vertex position
)
mesh:setIndexArray(
	1,2,3 -- 1. triangle from 1, 2 and 3 vertex
)
mesh:setColorArray(
	0xff0000,0.5, -- 1. vertex color and alpha
	0x00ff00,0.7, -- 2. vertex color and alpha
	0x0000ff,1.0 -- 3. vertex color and alpha
)

-- ok
mesh:setPosition(12*16, 8*16, -1*16)
stage:addChild(mesh)

mesh:addEventListener(Event.ENTER_FRAME, function(e)
	mesh:setRotationX(mesh:getRotationX()+1)
	mesh:setRotationY(mesh:getRotationY()+1)
	mesh:setRotation(mesh:getRotation()+1)
end)

A Rectangle

Take the triangle code above, add one vertex and you have two triangles that make a rectangle.

application:setBackgroundColor(0x323232)

-- Configures the field of view (fov) and far clipping plane for 3D projection
application:configureFrustum(45, -100) -- (fov, farplane)

local mesh = Mesh.new()

mesh:setVertexArray(
	0, 0, -- 1. vertex position
	100, 0, -- 2. vertex position
	100, 150, -- 3. vertex position
	0, 150 -- -- 4. vertex position
)
mesh:setIndexArray(
	1,2,3, -- 1. triangle from 1, 2 and 3 vertex
	1,3,4 -- 2. triangle from 1, 3 and 4 vertex
)
mesh:setColorArray(
	0xff0000,0.5, -- 1. vertex color and alpha
	0x00ff00,0.7, -- 2. vertex color and alpha
	0x0000ff,1.0, -- 3. vertex color and alpha
	0xffff00,0 -- 4. vertex color and alpha
)

-- ok
mesh:setPosition(12*16, 8*16, -1*16)
stage:addChild(mesh)

mesh:addEventListener(Event.ENTER_FRAME, function(e)
	mesh:setRotationX(mesh:getRotationX()+1)
	mesh:setRotationY(mesh:getRotationY()+1)
	mesh:setRotation(mesh:getRotation()+1)
end)

A Cube

In Gideros, a simple Sprite can be cube:

• we set the application 3D
• we create a local function to make the faces for our cube using Shape
• we add six faces (with appropriate rotation) to a parent Sprite
• and we are cube ;-)

application:setBackgroundColor(0x323232)

-- configure the field of view for 3D projection
application:configureFrustum(45) -- (fov, farplane)

-- create faces for a cube
local function face(color, rx, ry)
	local s = Shape.new()
	s:setFillStyle(Shape.SOLID, color, 0.7) -- translucent color
	s:beginPath()
	s:moveTo(-1,-1)
	s:lineTo(-1,1)
	s:lineTo(1,1)
	s:lineTo(1,-1)
	s:lineTo(-1,-1)
	s:endPath()
	-- orientation
	s:setRotationX(rx)
	s:setRotationY(ry)
	-- offset position -1 along its local Z axis
	s:setPosition(s:getMatrix():transformPoint(0, 0, -1))

	return s
end

-- a cube with 6 faces
cube = Sprite.new()
cube:addChild(face(0xFF8080, 0,0)) -- color, rx, ry
cube:addChild(face(0xFFFF00, 90,0)) -- color, rx, ry
cube:addChild(face(0xFF00FF, -90,0)) -- color, rx, ry
cube:addChild(face(0x80FF80, 180,0)) -- color, rx, ry
cube:addChild(face(0x00FFFF, 0,90)) -- color, rx, ry
cube:addChild(face(0x8080FF, 0,-90)) -- color, rx, ry

-- enable depth sorting for translucency
cube:setAutoSort(true)
cube:setScale(2*16, 2*16, 2*16)
cube:setPosition(12*16, 8*16, 1*16)

stage:addChild(cube)

-- Rotate our cube
cube:addEventListener(Event.ENTER_FRAME,function(e)
	cube:setRotationX(cube:getRotationX()+1)
	cube:setRotation(cube:getRotation()+1.3)
end)

Let's get real

A 3D Plane

So far we managed to be 3D using only the x and y axes. Let's get real and add the z axis:

• Mesh.new(true)

Initializing a Mesh with true makes the mesh expect a Z coordinate in its vertex array. Now this is real 3D 😉.

The principles are the same as flat 3D but with an extra axis to deal with. Let's introduce Texturing as well.

The raw:

application:setBackgroundColor(0x323232)

-- configure the field of view for 3D projection
application:configureFrustum(45) -- (fov, farplane)

local plane3d = Mesh.new(true) -- true = this mesh expects a Z coordinate in its vertex array 
local w, h, d = 5*8, 1*8, 10*8 -- 3d plane dimensions

local va = { -- vertex array
	-w,h,-d, -- 1. vertex position
	w,h,-d, -- 2. vertex position
	w,h,d, -- 3. vertex position
	-w,h,d, -- 4. vertex position
--	-w,h-30,d, -- 4. vertex position, test another position
}
local ia = { -- index array
	1,2,3, -- 1. triangle from 1, 2 and 3 vertex
	1,3,4, -- 2. triangle from 1, 3 and 4 vertex
}
plane3d:setVertexArray(va)
plane3d:setIndexArray(ia)

-- texture it
local tex = Texture.new("gfx/Aurichalcite Deposit.jpg", false, { wrap=Texture.REPEAT, } )
local tw,th = tex:getWidth()*0.5, tex:getHeight()*1 -- 0.5 and 1 are the texture scale (uv)
plane3d:setTextureCoordinateArray {
	0,0, -- 1. vertex texture coordinate
	tw,0, -- 2. vertex texture coordinate
	tw,th, -- 3. vertex texture coordinate
	0,th, -- 4. vertex texture coordinate
}
plane3d:setTexture(tex)

-- why no color
plane3d:setColor(1, 0xffffff, 1)
plane3d:setColor(2, 0x5500ff, 1)
plane3d:setColor(3, 0x000000, 1)
plane3d:setColor(4, 0xaaff00, 1)

-- ok
plane3d:setPosition(12*16, 10*16, -1*16)
stage:addChild(plane3d)

-- rotate it
plane3d:addEventListener(Event.ENTER_FRAME,function(e)
	plane3d:setRotationX(plane3d:getRotationX()+1)
	plane3d:setRotation(plane3d:getRotation()+1.3)
end)

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