445 lines
12 KiB
Go
445 lines
12 KiB
Go
package pixelgl
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import (
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"runtime"
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"unsafe"
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"github.com/go-gl/gl/v3.3-core/gl"
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"github.com/go-gl/mathgl/mgl32"
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"github.com/pkg/errors"
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)
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// VertexArray is an OpenGL vertex array object that also holds it's own vertex buffer object.
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// From the user's points of view, VertexArray is an array of vertices that can be drawn.
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type VertexArray struct {
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vao, vbo, ebo binder
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numVertices, numIndices int
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format AttrFormat
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stride int
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offset map[string]int
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}
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// NewVertexArray creates a new empty vertex array.
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//
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// You cannot specify vertex attributes in this constructor, only their count. Use
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// SetVertexAttribute* methods to set the vertex attributes. Use indices to specify how you
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// want to combine vertices into triangles.
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func NewVertexArray(shader *Shader, numVertices int, indices []int) (*VertexArray, error) {
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va := &VertexArray{
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vao: binder{
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restoreLoc: gl.VERTEX_ARRAY_BINDING,
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bindFunc: func(obj uint32) {
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gl.BindVertexArray(obj)
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},
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},
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vbo: binder{
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restoreLoc: gl.ARRAY_BUFFER_BINDING,
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bindFunc: func(obj uint32) {
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gl.BindBuffer(gl.ARRAY_BUFFER, obj)
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},
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},
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ebo: binder{
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restoreLoc: gl.ELEMENT_ARRAY_BUFFER_BINDING,
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bindFunc: func(obj uint32) {
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gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, obj)
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},
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},
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numVertices: numVertices,
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format: shader.VertexFormat(),
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stride: shader.VertexFormat().Size(),
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offset: make(map[string]int),
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}
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offset := 0
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for name, typ := range va.format {
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switch typ {
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case Float, Vec2, Vec3, Vec4:
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default:
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return nil, errors.New("failed to create vertex array: invalid attribute type")
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}
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va.offset[name] = offset
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offset += typ.Size()
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}
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gl.GenVertexArrays(1, &va.vao.obj)
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va.vao.bind()
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gl.GenBuffers(1, &va.vbo.obj)
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defer va.vbo.bind().restore()
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emptyData := make([]byte, numVertices*va.stride)
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gl.BufferData(gl.ARRAY_BUFFER, len(emptyData), gl.Ptr(emptyData), gl.DYNAMIC_DRAW)
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gl.GenBuffers(1, &va.ebo.obj)
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defer va.ebo.bind().restore()
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for name, typ := range va.format {
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loc := gl.GetAttribLocation(shader.ID(), gl.Str(name+"\x00"))
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var size int32
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switch typ {
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case Float:
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size = 1
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case Vec2:
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size = 2
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case Vec3:
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size = 3
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case Vec4:
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size = 4
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}
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gl.VertexAttribPointer(
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uint32(loc),
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size,
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gl.FLOAT,
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false,
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int32(va.stride),
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gl.PtrOffset(va.offset[name]),
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)
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gl.EnableVertexAttribArray(uint32(loc))
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}
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va.vao.restore()
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va.SetIndices(indices)
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runtime.SetFinalizer(va, (*VertexArray).delete)
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return va, nil
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}
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func (va *VertexArray) delete() {
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DoNoBlock(func() {
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gl.DeleteVertexArrays(1, &va.vao.obj)
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gl.DeleteBuffers(1, &va.vbo.obj)
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gl.DeleteBuffers(1, &va.ebo.obj)
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})
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}
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// ID returns an OpenGL identifier of a vertex array.
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func (va *VertexArray) ID() uint32 {
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return va.vao.obj
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}
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// NumVertices returns the number of vertices in a vertex array.
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func (va *VertexArray) NumVertices() int {
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return va.numVertices
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}
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// VertexFormat returns the format of the vertices inside a vertex array.
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//
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// Do not change this format!
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func (va *VertexArray) VertexFormat() AttrFormat {
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return va.format
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}
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// Draw draws a vertex array.
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//
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// The vertex array must be bound before calling this method.
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func (va *VertexArray) Draw() {
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gl.DrawElements(gl.TRIANGLES, int32(va.numIndices), gl.UNSIGNED_INT, gl.PtrOffset(0))
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}
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// SetIndices sets the indices of triangles to be drawn. Triangles will be formed from the
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// vertices of the array as defined by these indices. The first drawn triangle is specified by
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// the first three indices, the second by the fourth through sixth and so on.
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//
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// The vertex array must be bound before calling this method.
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func (va *VertexArray) SetIndices(indices []int) {
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if len(indices)%3 != 0 {
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panic("vertex array set indices: number of indices not divisible by 3")
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}
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indices32 := make([]uint32, len(indices))
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for i := range indices32 {
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indices32[i] = uint32(indices[i])
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}
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va.numIndices = len(indices32)
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gl.BufferData(gl.ELEMENT_ARRAY_BUFFER, 4*len(indices32), gl.Ptr(indices32), gl.DYNAMIC_DRAW)
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}
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// Indices returns the current indices of triangles to be drawn.
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//
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// The vertex array must be bound before calling this method.
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func (va *VertexArray) Indices() []int {
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indices32 := make([]uint32, va.numIndices)
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gl.GetBufferSubData(gl.ELEMENT_ARRAY_BUFFER, 0, 4*len(indices32), gl.Ptr(indices32))
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indices := make([]int, len(indices32))
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for i := range indices {
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indices[i] = int(indices32[i])
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}
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return indices
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}
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// SetVertexAttr sets the value of the specified vertex attribute of the specified vertex.
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//
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// If the vertex attribute does not exist, this method returns false. If the vertex is out of
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// range, this method panics.
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//
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// Supplied value must correspond to the type of the attribute. Correct types are these
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// (righ-hand is the type of the value):
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// Attr{Type: Float}: float32
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// Attr{Type: Vec2}: mgl32.Vec2
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// Attr{Type: Vec3}: mgl32.Vec3
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// Attr{Type: Vec4}: mgl32.Vec4
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// No other types are supported.
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//
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// The vertex array must be bound before calling this method.
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func (va *VertexArray) SetVertexAttr(vertex int, attr Attr, value interface{}) (ok bool) {
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if vertex < 0 || vertex >= va.numVertices {
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panic("set vertex attr: invalid vertex index")
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}
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if !va.format.Contains(attr) {
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return false
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}
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offset := va.stride*vertex + va.offset[attr.Name]
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switch attr.Type {
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case Float:
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value := value.(float32)
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gl.BufferSubData(gl.ARRAY_BUFFER, offset, attr.Type.Size(), unsafe.Pointer(&value))
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case Vec2:
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value := value.(mgl32.Vec2)
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gl.BufferSubData(gl.ARRAY_BUFFER, offset, attr.Type.Size(), unsafe.Pointer(&value))
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case Vec3:
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value := value.(mgl32.Vec3)
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gl.BufferSubData(gl.ARRAY_BUFFER, offset, attr.Type.Size(), unsafe.Pointer(&value))
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case Vec4:
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value := value.(mgl32.Vec4)
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gl.BufferSubData(gl.ARRAY_BUFFER, offset, attr.Type.Size(), unsafe.Pointer(&value))
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default:
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panic("set vertex attr: invalid attribute type")
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}
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return true
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}
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// VertexAttr returns the current value of the specified vertex attribute of the specified vertex.
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//
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// If the vertex attribute does not exist, this method returns nil and false. If the vertex is
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// out of range, this method panics.
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//
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// The type of the returned value follows the same rules as with SetVertexAttr.
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//
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// The vertex array must be bound before calling this method.
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func (va *VertexArray) VertexAttr(vertex int, attr Attr) (value interface{}, ok bool) {
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if vertex < 0 || vertex >= va.numVertices {
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panic("vertex attr: invalid vertex index")
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}
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if !va.format.Contains(attr) {
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return nil, false
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}
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offset := va.stride*vertex + va.offset[attr.Name]
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switch attr.Type {
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case Float:
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var data float32
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gl.GetBufferSubData(gl.ARRAY_BUFFER, offset, attr.Type.Size(), unsafe.Pointer(&data))
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value = data
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case Vec2:
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var data mgl32.Vec2
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gl.GetBufferSubData(gl.ARRAY_BUFFER, offset, attr.Type.Size(), unsafe.Pointer(&data))
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value = data
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case Vec3:
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var data mgl32.Vec3
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gl.GetBufferSubData(gl.ARRAY_BUFFER, offset, attr.Type.Size(), unsafe.Pointer(&data))
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value = data
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case Vec4:
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var data mgl32.Vec4
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gl.GetBufferSubData(gl.ARRAY_BUFFER, offset, attr.Type.Size(), unsafe.Pointer(&data))
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value = data
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default:
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panic("set vertex attr: invalid attribute type")
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}
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return value, true
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}
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// SetVertex sets values of the attributes specified in the supplied map. All other attributes
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// will be set to zero.
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//
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// Not existing attributes are silently skipped.
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//
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// The vertex array must be bound before calling this method.
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func (va *VertexArray) SetVertex(vertex int, values map[Attr]interface{}) {
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if vertex < 0 || vertex >= va.numVertices {
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panic("set vertex: invalid vertex index")
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}
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data := make([]float32, va.format.Size()/4)
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for attr, value := range values {
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if !va.format.Contains(attr) {
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continue
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}
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offset := va.offset[attr.Name]
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switch attr.Type {
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case Float:
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data[offset/4] = value.(float32)
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case Vec2:
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value := value.(mgl32.Vec2)
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copy(data[offset/4:offset/4+attr.Type.Size()/4], value[:])
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case Vec3:
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value := value.(mgl32.Vec3)
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copy(data[offset/4:offset/4+attr.Type.Size()/4], value[:])
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case Vec4:
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value := value.(mgl32.Vec4)
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copy(data[offset/4:offset/4+attr.Type.Size()/4], value[:])
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default:
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panic("set vertex: invalid attribute type")
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}
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}
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offset := va.stride * vertex
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gl.BufferSubData(gl.ARRAY_BUFFER, offset, len(data)*4, gl.Ptr(data))
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}
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// Vertex returns values of all vertex attributes of the specified vertex in a map.
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//
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// The vertex array must be bound before calling this method.
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func (va *VertexArray) Vertex(vertex int) (values map[Attr]interface{}) {
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if vertex < 0 || vertex >= va.numVertices {
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panic("set vertex: invalid vertex index")
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}
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data := make([]float32, va.format.Size()/4)
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offset := va.stride * vertex
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gl.GetBufferSubData(gl.ARRAY_BUFFER, offset, len(data)*4, gl.Ptr(data))
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values = make(map[Attr]interface{})
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for name, typ := range va.format {
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attr := Attr{name, typ}
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offset := va.offset[attr.Name]
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switch attr.Type {
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case Float:
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values[attr] = data[offset/4]
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case Vec2:
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var value mgl32.Vec2
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copy(value[:], data[offset/4:offset/4+attr.Type.Size()/4])
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values[attr] = value
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case Vec3:
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var value mgl32.Vec3
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copy(value[:], data[offset/4:offset/4+attr.Type.Size()/4])
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values[attr] = value
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case Vec4:
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var value mgl32.Vec4
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copy(value[:], data[offset/4:offset/4+attr.Type.Size()/4])
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values[attr] = value
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}
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}
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return values
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}
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// SetVertices sets values of vertex attributes of all vertices as specified in the supplied
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// slice of maps. If the length of vertices does not match the number of vertices in the vertex
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// array, this method panics.
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//
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// Not existing attributes are silently skipped.
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//
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// The vertex array must be bound before calling this metod.
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func (va *VertexArray) SetVertices(vertices []map[Attr]interface{}) {
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if len(vertices) != va.numVertices {
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panic("set vertex array: wrong number of supplied vertices")
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}
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data := make([]float32, va.numVertices*va.format.Size()/4)
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for vertex := range vertices {
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for attr, value := range vertices[vertex] {
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if !va.format.Contains(attr) {
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continue
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}
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offset := va.stride*vertex + va.offset[attr.Name]
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switch attr.Type {
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case Float:
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data[offset/4] = value.(float32)
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case Vec2:
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value := value.(mgl32.Vec2)
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copy(data[offset/4:offset/4+attr.Type.Size()/4], value[:])
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case Vec3:
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value := value.(mgl32.Vec3)
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copy(data[offset/4:offset/4+attr.Type.Size()/4], value[:])
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case Vec4:
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value := value.(mgl32.Vec4)
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copy(data[offset/4:offset/4+attr.Type.Size()/4], value[:])
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default:
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panic("set vertex: invalid attribute type")
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}
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}
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}
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gl.BufferSubData(gl.ARRAY_BUFFER, 0, len(data)*4, gl.Ptr(data))
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}
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// Vertices returns values of vertex attributes of all vertices in a vertex array in a slice
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// of maps.
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//
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// The vertex array must be bound before calling this metod.
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func (va *VertexArray) Vertices() (vertices []map[Attr]interface{}) {
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data := make([]float32, va.numVertices*va.format.Size()/4)
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gl.GetBufferSubData(gl.ARRAY_BUFFER, 0, len(data)*4, gl.Ptr(data))
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vertices = make([]map[Attr]interface{}, va.numVertices)
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for vertex := range vertices {
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values := make(map[Attr]interface{})
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for name, typ := range va.format {
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attr := Attr{name, typ}
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offset := va.stride*vertex + va.offset[attr.Name]
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switch attr.Type {
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case Float:
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values[attr] = data[offset/4]
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case Vec2:
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var value mgl32.Vec2
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copy(value[:], data[offset/4:offset/4+attr.Type.Size()/4])
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values[attr] = value
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case Vec3:
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var value mgl32.Vec3
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copy(value[:], data[offset/4:offset/4+attr.Type.Size()/4])
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values[attr] = value
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case Vec4:
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var value mgl32.Vec4
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copy(value[:], data[offset/4:offset/4+attr.Type.Size()/4])
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values[attr] = value
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}
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}
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vertices[vertex] = values
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}
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return vertices
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}
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// Begin binds a vertex array. This is neccessary before using the vertex array.
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func (va *VertexArray) Begin() {
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va.vao.bind()
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va.vbo.bind()
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va.ebo.bind()
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}
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// End unbinds a vertex array and restores the previous one.
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func (va *VertexArray) End() {
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va.ebo.restore()
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va.vbo.restore()
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va.vao.restore()
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}
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