106 lines
2.6 KiB
Go
106 lines
2.6 KiB
Go
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package cylinder
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import (
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"zworld/engine/object"
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"zworld/engine/object/mesh"
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"zworld/engine/renderapi/color"
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"zworld/engine/renderapi/material"
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"zworld/engine/renderapi/vertex"
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"zworld/plugins/math"
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"zworld/plugins/math/vec3"
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)
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type Cylinder struct {
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object.Object
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Mesh *Mesh
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}
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func NewObject(args Args) *Cylinder {
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return object.New("Cylinder", &Cylinder{
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Mesh: New(args),
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})
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}
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// A Cylinder is a forward rendered colored cyllinder mesh
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type Mesh struct {
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*mesh.Static
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Args
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}
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type Args struct {
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Mat *material.Def
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Radius float32
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Height float32
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Segments int
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Color color.T
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}
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func New(args Args) *Mesh {
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if args.Mat == nil {
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args.Mat = material.ColoredForward()
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}
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cyllinder := object.NewComponent(&Mesh{
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Static: mesh.New(args.Mat),
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Args: args,
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})
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// this should not run on the main thread
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cyllinder.generate()
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return cyllinder
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}
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func (c *Mesh) generate() {
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// vertex order: clockwise
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data := make([]vertex.C, 2*2*3*c.Segments)
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hh := c.Height / 2
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sangle := 2 * math.Pi / float32(c.Segments)
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color := c.Color.Vec4()
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// top
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top := vec3.New(0, hh, 0)
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bottom := vec3.New(0, -hh, 0)
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for i := 0; i < c.Segments; i++ {
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o := 12 * i // segment vertex offset
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right := sangle * (float32(i) + 0.5)
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left := sangle * (float32(i) + 1.5)
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topRight := vec3.New(math.Cos(right), 0, -math.Sin(right)).Scaled(c.Radius)
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topRight.Y = hh
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topLeft := vec3.New(math.Cos(left), 0, -math.Sin(left)).Scaled(c.Radius)
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topLeft.Y = hh
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bottomRight := vec3.New(math.Cos(right), 0, -math.Sin(right)).Scaled(c.Radius)
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bottomRight.Y = -hh
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bottomLeft := vec3.New(math.Cos(left), 0, -math.Sin(left)).Scaled(c.Radius)
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bottomLeft.Y = -hh
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// top face
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data[o+0] = vertex.C{P: topLeft, N: vec3.Up, C: color}
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data[o+1] = vertex.C{P: top, N: vec3.Up, C: color}
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data[o+2] = vertex.C{P: topRight, N: vec3.Up, C: color}
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// bottom face
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data[o+3] = vertex.C{P: bottomRight, N: vec3.Down, C: color}
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data[o+4] = vertex.C{P: bottom, N: vec3.Down, C: color}
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data[o+5] = vertex.C{P: bottomLeft, N: vec3.Down, C: color}
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// calculate segment normal
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nv1 := topRight.Sub(bottomLeft)
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nv2 := bottomRight.Sub(bottomLeft)
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n := vec3.Cross(nv1, nv2)
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// side face 1
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data[o+6] = vertex.C{P: topRight, N: n, C: color}
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data[o+7] = vertex.C{P: bottomLeft, N: n, C: color}
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data[o+8] = vertex.C{P: topLeft, N: n, C: color}
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// side face 2
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data[o+9] = vertex.C{P: bottomRight, N: n, C: color}
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data[o+10] = vertex.C{P: bottomLeft, N: n, C: color}
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data[o+11] = vertex.C{P: topRight, N: n, C: color}
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}
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key := object.Key("cylinder", c)
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mesh := vertex.NewTriangles(key, data, []uint16{})
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c.VertexData.Set(mesh)
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}
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