object3d.go

package three

import (
	"github.com/go-gl/gl"
	"github.com/go-gl/mathgl/mgl32"
)

// Object3D described an object in 3D space.
type Object3D struct {
	vertexBuffer gl.Buffer
	uvBuffer     gl.Buffer
	normalBuffer gl.Buffer
	index        *Index

	transform *Transform
}

// NewObject3D returns a new Object3D. It initializes the transform
// of the object.
func NewObject3D() Object3D {
	o := Object3D{
		transform: NewTransform(),
	}

	return o
}

// Index returns the FBO index.
func (o *Object3D) Index() *Index {
	return o.index
}

// Transform returns the transform object (translation, rotation, scale) for this object.
func (o *Object3D) Transform() *Transform {
	return o.transform
}

// UVBuffer returns the buffer object for this objects uvs.
func (o *Object3D) UVBuffer() gl.Buffer {
	return o.uvBuffer
}

// VertexBuffer returns the buffer object for this objects vertices.
func (o *Object3D) VertexBuffer() gl.Buffer {
	return o.vertexBuffer
}

// NormalBuffer returns the buffer object for this objects normals.
func (o *Object3D) NormalBuffer() gl.Buffer {
	return o.normalBuffer
}

func newUvBuffer(uvs []mgl32.Vec2, compressed bool) gl.Buffer {
	result := []float32{}

	for _, uv := range uvs {
		result = append(result, uv.X(), uv.Y())
	}

	if compressed {
		// Invert V because we're using a compressed texture
		for i := 1; i < len(result); i += 2 {
			result[i] = 1.0 - result[i]
		}
	}

	glBuffer := gl.GenBuffer()
	glBuffer.Bind(gl.ARRAY_BUFFER)
	gl.BufferData(gl.ARRAY_BUFFER, len(result)*2*4, result, gl.STATIC_DRAW)

	return glBuffer
}

func newVertexBuffer(geometry Shape) gl.Buffer {
	result := []float32{}

	faces := geometry.Faces()
	vertices := geometry.Vertices()

	if len(faces) > 0 {
		// Handle faces
		for _, face := range faces {
			for i := 0; i < 3; i++ {
				vertex := vertices[face.At(i)]
				result = append(result, vertex.X(), vertex.Y(), vertex.Z())
			}
		}
	} else {
		// Handle plain vertices
		for _, vertex := range geometry.Vertices() {
			result = append(result, vertex.X(), vertex.Y(), vertex.Z())
		}
	}

	glBuffer := gl.GenBuffer()
	glBuffer.Bind(gl.ARRAY_BUFFER)
	gl.BufferData(gl.ARRAY_BUFFER, len(result)*3*4, result, gl.STATIC_DRAW)

	return glBuffer
}

func newNormalBuffer(geometry Shape) gl.Buffer {
	result := []float32{}

	normals := geometry.Normals()

	for _, face := range geometry.Faces() {
		for i := 0; i < 3; i++ {
			normal := normals[face.NormalAt(i)]
			result = append(result, normal.X(), normal.Y(), normal.Z())
		}
	}

	glBuffer := gl.GenBuffer()
	glBuffer.Bind(gl.ARRAY_BUFFER)
	gl.BufferData(gl.ARRAY_BUFFER, len(result)*3*4, result, gl.STATIC_DRAW)

	return glBuffer
}

func generateIndex(geometry Shape) *Index {
	// Disabled VBO index for now
	// data := []uint16{}

	// for _, f := range geometry.Faces() {
	// 	data = append(data, f.A(), f.B(), f.C())
	// }

	index := &Index{count: 0}
	return index
}