Primitive shapes

main.go

@@ -27,7 +27,7 @@ func LoadPrimitives() error {
 func GetModel(conf ModelReaderConf, desiredSize MeshTypes.Vector) (*MeshTypes.Mesh, error) {
 	var mesh *MeshTypes.Mesh
 
-	if conf.PrimitiveType == "Undefined" && conf.File != nil && conf.Filename != nil && *conf.Filename != "" {
+	if conf.File != nil && conf.Filename != nil && *conf.Filename != "" {
 		filetype := filepath.Ext(*conf.Filename)
 		switch filetype {
 		case ".gltf", ".glb":
@@ -48,15 +48,13 @@ func GetModel(conf ModelReaderConf, desiredSize MeshTypes.Vector) (*MeshTypes.Me
 		default:
 			return nil, fmt.Errorf("unknown model type %s", filetype)
 		}
-	} else if conf.PrimitiveType != "Undefined" {
+	} else {
 		if Primitives.Primitives[conf.PrimitiveType] == nil {
 			return nil, fmt.Errorf("unknown primitive type %s", conf.PrimitiveType)
 		}
 		tempMesh := Primitives.Primitives[conf.PrimitiveType].Copy()
 		mesh = &tempMesh
 		mesh.ScaleToDimensions(&desiredSize)
-	} else {
-		return nil, fmt.Errorf("invalid ModelReader config")
 	}
 
 	return mesh, nil

pkg/MeshTypes/vector.go

@@ -1,5 +1,26 @@
 package MeshTypes
 
+// Copyright (c) 2025 Michael Fogleman
+// Portions adapted from FauxGL (https://github.com/fogleman/fauxgl)
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the “Software”), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
 import "math"
 
 type Vector struct {
@@ -8,6 +29,10 @@ type Vector struct {
 	Z float64
 }
 
+func (a Vector) DivScalar(b float64) Vector {
+	return Vector{a.X / b, a.Y / b, a.Z / b}
+}
+
 func (a Vector) Add(b Vector) Vector {
 	return Vector{a.X + b.X, a.Y + b.Y, a.Z + b.Z}
 }

pkg/primitives/cube.go

@@ -0,0 +1,81 @@
+package Primitives
+
+import Types "github.com/Patch2PDF/GDTF-Mesh-Reader/pkg/MeshTypes"
+
+func NewCube() Types.Mesh {
+	v := []Types.Vector{
+		{X: -1, Y: 1, Z: -1}, {X: -1, Y: 1, Z: 1}, {X: 1, Y: 1, Z: 1}, {X: 1, Y: 1, Z: -1},
+		{X: -1, Y: -1, Z: -1}, {X: -1, Y: -1, Z: 1}, {X: 1, Y: -1, Z: 1}, {X: 1, Y: -1, Z: -1},
+	}
+	mesh := Types.Mesh{
+		Triangles: []*Types.Triangle{
+			// top
+			{
+				V0: &Types.Vertex{Position: v[1], Normal: nil},
+				V1: &Types.Vertex{Position: v[2], Normal: nil},
+				V2: &Types.Vertex{Position: v[3], Normal: nil},
+			},
+			{
+				V0: &Types.Vertex{Position: v[0], Normal: nil},
+				V1: &Types.Vertex{Position: v[1], Normal: nil},
+				V2: &Types.Vertex{Position: v[3], Normal: nil},
+			},
+			// left
+			{
+				V0: &Types.Vertex{Position: v[4], Normal: nil},
+				V1: &Types.Vertex{Position: v[1], Normal: nil},
+				V2: &Types.Vertex{Position: v[0], Normal: nil},
+			},
+			{
+				V0: &Types.Vertex{Position: v[4], Normal: nil},
+				V1: &Types.Vertex{Position: v[5], Normal: nil},
+				V2: &Types.Vertex{Position: v[1], Normal: nil},
+			},
+			// front
+			{
+				V0: &Types.Vertex{Position: v[5], Normal: nil},
+				V1: &Types.Vertex{Position: v[2], Normal: nil},
+				V2: &Types.Vertex{Position: v[1], Normal: nil},
+			},
+			{
+				V0: &Types.Vertex{Position: v[5], Normal: nil},
+				V1: &Types.Vertex{Position: v[6], Normal: nil},
+				V2: &Types.Vertex{Position: v[2], Normal: nil},
+			},
+			// right
+			{
+				V0: &Types.Vertex{Position: v[7], Normal: nil},
+				V1: &Types.Vertex{Position: v[3], Normal: nil},
+				V2: &Types.Vertex{Position: v[2], Normal: nil},
+			},
+			{
+				V0: &Types.Vertex{Position: v[7], Normal: nil},
+				V1: &Types.Vertex{Position: v[2], Normal: nil},
+				V2: &Types.Vertex{Position: v[6], Normal: nil},
+			},
+			// back
+			{
+				V0: &Types.Vertex{Position: v[0], Normal: nil},
+				V1: &Types.Vertex{Position: v[3], Normal: nil},
+				V2: &Types.Vertex{Position: v[4], Normal: nil},
+			},
+			{
+				V0: &Types.Vertex{Position: v[7], Normal: nil},
+				V1: &Types.Vertex{Position: v[4], Normal: nil},
+				V2: &Types.Vertex{Position: v[3], Normal: nil},
+			},
+			// bottom
+			{
+				V0: &Types.Vertex{Position: v[6], Normal: nil},
+				V1: &Types.Vertex{Position: v[5], Normal: nil},
+				V2: &Types.Vertex{Position: v[4], Normal: nil},
+			},
+			{
+				V0: &Types.Vertex{Position: v[7], Normal: nil},
+				V1: &Types.Vertex{Position: v[6], Normal: nil},
+				V2: &Types.Vertex{Position: v[4], Normal: nil},
+			},
+		},
+	}
+	return mesh
+}

pkg/primitives/cylinder.go

@@ -0,0 +1,62 @@
+package Primitives
+
+// Copyright (c) 2025 Michael Fogleman
+// Portions adapted from FauxGL (https://github.com/fogleman/fauxgl)
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the “Software”), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+import (
+	"math"
+
+	Types "github.com/Patch2PDF/GDTF-Mesh-Reader/pkg/MeshTypes"
+)
+
+func radians(degrees float64) float64 {
+	return degrees * math.Pi / 180
+}
+
+func NewCylinder(step int, capped bool) Types.Mesh {
+	var triangles []*Types.Triangle
+	for a0 := 0; a0 < 360; a0 += step {
+		a1 := (a0 + step) % 360
+		r0 := radians(float64(a0))
+		r1 := radians(float64(a1))
+		x0 := math.Cos(r0)
+		y0 := math.Sin(r0)
+		x1 := math.Cos(r1)
+		y1 := math.Sin(r1)
+		p00 := Types.Vector{X: x0, Y: y0, Z: -0.5}
+		p10 := Types.Vector{X: x1, Y: y1, Z: -0.5}
+		p11 := Types.Vector{X: x1, Y: y1, Z: 0.5}
+		p01 := Types.Vector{X: x0, Y: y0, Z: 0.5}
+		t1 := &Types.Triangle{V0: p00.ToVertex(nil), V1: p10.ToVertex(nil), V2: p11.ToVertex(nil)}
+		t2 := &Types.Triangle{V0: p00.ToVertex(nil), V1: p11.ToVertex(nil), V2: p01.ToVertex(nil)}
+		triangles = append(triangles, t1)
+		triangles = append(triangles, t2)
+		if capped {
+			p0 := Types.Vector{X: 0, Y: 0, Z: -0.5}
+			p1 := Types.Vector{X: 0, Y: 0, Z: 0.5}
+			t3 := &Types.Triangle{V0: p0.ToVertex(nil), V1: p10.ToVertex(nil), V2: p00.ToVertex(nil)}
+			t4 := &Types.Triangle{V0: p1.ToVertex(nil), V1: p01.ToVertex(nil), V2: p11.ToVertex(nil)}
+			triangles = append(triangles, t3)
+			triangles = append(triangles, t4)
+		}
+	}
+	return Types.Mesh{Triangles: triangles}
+}

pkg/primitives/primitives.go

@@ -30,16 +30,30 @@ var Primitives = map[string]*Types.Mesh{}
 
 func LoadPrimitives() error {
 	for primitiveType, path := range primitivePaths {
-		if path == "" {
-			continue
-		}
-		data, err := modelFS.ReadFile(path)
-		if err != nil {
-			return err
-		}
-		Primitives[primitiveType], err = FileHandlers.Load3DS(&data, nil)
-		if err != nil {
-			return err
+		switch primitiveType {
+		case "Cube":
+			mesh := NewCube()
+			Primitives[primitiveType] = &mesh
+		case "Cylinder":
+			mesh := NewCylinder(10, true)
+			Primitives[primitiveType] = &mesh
+		case "Sphere":
+			mesh := NewSphere(2)
+			Primitives[primitiveType] = &mesh
+		case "Pigtail":
+			Primitives[primitiveType] = &Types.Mesh{} // empty mesh
+		default:
+			if path == "" {
+				continue
+			}
+			data, err := modelFS.ReadFile(path)
+			if err != nil {
+				return err
+			}
+			Primitives[primitiveType], err = FileHandlers.Load3DS(&data, nil)
+			if err != nil {
+				return err
+			}
 		}
 	}
 	return nil

pkg/primitives/sphere.go

@@ -0,0 +1,109 @@
+package Primitives
+
+// Copyright (c) 2025 Michael Fogleman
+// Portions adapted from FauxGL (https://github.com/fogleman/fauxgl)
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the “Software”), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+import Types "github.com/Patch2PDF/GDTF-Mesh-Reader/pkg/MeshTypes"
+
+func NewSphere(detail int) Types.Mesh {
+	var triangles []*Types.Triangle
+	ico := NewIcosahedron()
+	for _, t := range ico.Triangles {
+		v1 := t.V0.Position
+		v2 := t.V1.Position
+		v3 := t.V2.Position
+		triangles = append(triangles, newSphereHelper(detail, v1, v2, v3)...)
+	}
+	return Types.Mesh{Triangles: triangles}
+}
+
+func newSphereHelper(detail int, v1, v2, v3 Types.Vector) []*Types.Triangle {
+	if detail == 0 {
+		t := &Types.Triangle{
+			V0: v1.ToVertex(nil),
+			V1: v2.ToVertex(nil),
+			V2: v3.ToVertex(nil),
+		}
+		return []*Types.Triangle{t}
+	}
+	var triangles []*Types.Triangle
+	v12 := v1.Add(v2).DivScalar(2).Normalize()
+	v13 := v1.Add(v3).DivScalar(2).Normalize()
+	v23 := v2.Add(v3).DivScalar(2).Normalize()
+	triangles = append(triangles, newSphereHelper(detail-1, v1, v12, v13)...)
+	triangles = append(triangles, newSphereHelper(detail-1, v2, v23, v12)...)
+	triangles = append(triangles, newSphereHelper(detail-1, v3, v13, v23)...)
+	triangles = append(triangles, newSphereHelper(detail-1, v12, v23, v13)...)
+	return triangles
+}
+
+func NewIcosahedron() *Types.Mesh {
+	const a = 0.8506507174597755
+	const b = 0.5257312591858783
+	vertices := []Types.Vector{
+		{X: -a, Y: -b, Z: 0},
+		{X: -a, Y: b, Z: 0},
+		{X: -b, Y: 0, Z: -a},
+		{X: -b, Y: 0, Z: a},
+		{X: 0, Y: -a, Z: -b},
+		{X: 0, Y: -a, Z: b},
+		{X: 0, Y: a, Z: -b},
+		{X: 0, Y: a, Z: b},
+		{X: b, Y: 0, Z: -a},
+		{X: b, Y: 0, Z: a},
+		{X: a, Y: -b, Z: 0},
+		{X: a, Y: b, Z: 0},
+	}
+	indices := [][3]int{
+		{0, 3, 1},
+		{1, 3, 7},
+		{2, 0, 1},
+		{2, 1, 6},
+		{4, 0, 2},
+		{4, 5, 0},
+		{5, 3, 0},
+		{6, 1, 7},
+		{6, 7, 11},
+		{7, 3, 9},
+		{8, 2, 6},
+		{8, 4, 2},
+		{8, 6, 11},
+		{8, 10, 4},
+		{8, 11, 10},
+		{9, 3, 5},
+		{10, 5, 4},
+		{10, 9, 5},
+		{11, 7, 9},
+		{11, 9, 10},
+	}
+	triangles := make([]*Types.Triangle, len(indices))
+	for i, idx := range indices {
+		p1 := vertices[idx[0]]
+		p2 := vertices[idx[1]]
+		p3 := vertices[idx[2]]
+		triangles[i] = &Types.Triangle{
+			V0: p1.ToVertex(nil),
+			V1: p2.ToVertex(nil),
+			V2: p3.ToVertex(nil),
+		}
+	}
+	return &Types.Mesh{Triangles: triangles}
+}

tests/MeshTypes/vector_test.go

@@ -7,6 +7,19 @@ import (
 	"github.com/Patch2PDF/GDTF-Mesh-Reader/pkg/MeshTypes"
 )
 
+func TestVectorDivScalar(t *testing.T) {
+	a := MeshTypes.Vector{
+		X: 2, Y: 4, Z: 6,
+	}
+	b := 2.0
+	want := MeshTypes.Vector{
+		X: 1, Y: 2, Z: 3,
+	}
+	if !reflect.DeepEqual(a.DivScalar(b), want) {
+		t.Error("Vector DivScalar() returned value does not match expected value")
+	}
+}
+
 func TestVectorAdd(t *testing.T) {
 	a := MeshTypes.Vector{
 		X: 1, Y: 2, Z: 3,