go-opengl-pixel/graphics.go

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package pixel
import (
"image/color"
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"math"
"github.com/faiface/pixel/pixelgl"
"github.com/go-gl/mathgl/mgl32"
"github.com/pkg/errors"
)
// Drawer is anything that can be drawn. It's by no means a drawer inside your table.
//
// Drawer consists of a single methods: Draw. Draw methods takes any number of Transform
// arguments. It applies these transforms in the reverse order and finally draws something
// transformed by these transforms.
//
// Example:
//
// // object is a drawer
// object.Draw(pixel.Position(pixel.V(100, 100).Rotate(math.Pi / 2)))
// camera := pixel.Camera(pixel.V(0, 0), pixel.V(500, 500), pixel.V(window.Size()))
// object.Draw(camera, pixel.Position(0).Scale(0.5))
type Drawer interface {
Draw(t ...Transform)
}
// Group is used to effeciently handle a collection of objects with a common parent. Usually many
// objects share a parent, using a group can significantly increase performance in these cases.
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//
// To use a group, first, create a group and as it's parent use the common parent of the
// collection of objects:
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//
// group := pixel.NewGroup(commonParent)
//
// Then, when creating the objects, use the group as their parent, instead of the original
// common parent, but, don't forget to put everything into a With block, like this:
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//
// group.With(func() {
// object := newArbitratyObject(group, ...) // group is the parent of the object
// })
//
// When dealing with objects associated with a group, it's always necessary to wrap that into
// a With block:
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//
// group.With(func() {
// for _, obj := range objectsWithCommonParent {
// // do something with obj
// }
// })
//
// That's all!
type Group struct {
parent pixelgl.Doer
context pixelgl.Context
}
// NewGroup creates a new group with the specified parent.
func NewGroup(parent pixelgl.Doer) *Group {
return &Group{
parent: parent,
}
}
// With enables the parent of a group and executes sub.
func (g *Group) With(sub func()) {
g.parent.Do(func(ctx pixelgl.Context) {
g.context = ctx
sub()
})
}
// Do just passes a cached context to sub.
func (g *Group) Do(sub func(pixelgl.Context)) {
sub(g.context)
}
// Shape is a general drawable shape constructed from vertices.
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//
// Vertices are specified in the vertex array of a shape. A shape can have a picture, a color
// (mask) and a static transform.
//
// Usually you use this type only indirectly throught other specific shapes (sprites, polygons,
// ...) embedding it.
type Shape struct {
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parent pixelgl.Doer
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picture *Picture
color color.Color
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transform Transform
va *pixelgl.VertexArray
}
// NewShape creates a new shape with specified parent, picture, color, transform and vertex array.
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func NewShape(parent pixelgl.Doer, picture *Picture, c color.Color, transform Transform, va *pixelgl.VertexArray) *Shape {
return &Shape{
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parent: parent,
picture: picture,
color: c,
transform: transform,
va: va,
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}
}
// SetPicture changes the picture of a shape.
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func (s *Shape) SetPicture(picture *Picture) {
s.picture = picture
}
// Picture returns the current picture of a shape.
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func (s *Shape) Picture() *Picture {
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return s.picture
}
// SetColor changes the color (mask) of a shape.
func (s *Shape) SetColor(c color.Color) {
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s.color = c
}
// Color returns the current color (mask) of a shape.
func (s *Shape) Color() color.Color {
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return s.color
}
// SetTransform changes the ("static") transform of a shape.
func (s *Shape) SetTransform(transform Transform) {
s.transform = transform
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}
// Transform returns the current ("static") transform of a shape.
func (s *Shape) Transform() Transform {
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return s.transform
}
// VertexArray changes the underlying vertex array of a shape.
func (s *Shape) VertexArray() *pixelgl.VertexArray {
return s.va
}
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// Draw draws a sprite transformed by the supplied transforms applied in the reverse order.
func (s *Shape) Draw(t ...Transform) {
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mat := mgl32.Ident3()
for i := range t {
mat = mat.Mul3(t[i].Mat())
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}
mat = mat.Mul3(s.transform.Mat())
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s.parent.Do(func(ctx pixelgl.Context) {
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c := NRGBAModel.Convert(s.color).(NRGBA)
ctx.Shader().SetUniformAttr(maskColorVec4, mgl32.Vec4{float32(c.R), float32(c.G), float32(c.B), float32(c.A)})
ctx.Shader().SetUniformAttr(transformMat3, mat)
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if s.picture != nil {
s.picture.Texture().Do(func(pixelgl.Context) {
s.va.Draw()
})
} else {
s.va.Draw()
}
})
}
// MultiShape is a shape composed of several other shapes. These shapes cannot be modifies
// after combined into a multishape.
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//
// Using a multishape can greatly increase drawing performance. However, it's only usable when
// the relative transformations of the shapes don't change (e.g. static blocks in a level).
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//
// All shapes in a multishape must share the same texture (or use no texture).
type MultiShape struct {
*Shape
}
// NewMultiShape creates a new multishape from several other shapes.
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//
// If two of the supplied shapes have different pictures, this function panics.
func NewMultiShape(parent pixelgl.Doer, shapes ...*Shape) *MultiShape {
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var picture *Picture
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for _, shape := range shapes {
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if picture != nil && shape.Picture() != nil && shape.Picture().Texture().ID() != picture.Texture().ID() {
panic(errors.New("failed to create multishape: shapes have different pictures"))
}
if shape.Picture() != nil {
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picture = shape.Picture()
}
}
var va *pixelgl.VertexArray
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var indices []int
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offset := 0
for _, shape := range shapes {
for _, i := range shape.va.Indices() {
indices = append(indices, offset+i)
}
offset += shape.VertexArray().NumVertices()
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}
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var vertices []map[pixelgl.Attr]interface{}
for _, shape := range shapes {
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shapeVertices := shape.VertexArray().Vertices()
for vertex := range shapeVertices {
if pos, ok := shapeVertices[vertex][positionVec2]; ok {
pos := pos.(mgl32.Vec2)
pos = shape.Transform().Mat().Mul3x1(mgl32.Vec3{pos.X(), pos.Y(), 1}).Vec2()
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shapeVertices[vertex][positionVec2] = pos
}
if color, ok := shapeVertices[vertex][colorVec4]; ok {
color := color.(mgl32.Vec4)
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c := NRGBAModel.Convert(shape.Color()).(NRGBA)
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color = mgl32.Vec4{
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color[0] * float32(c.R),
color[1] * float32(c.G),
color[2] * float32(c.B),
color[3] * float32(c.A),
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}
shapeVertices[vertex][colorVec4] = color
}
}
vertices = append(vertices, shapeVertices...)
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}
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parent.Do(func(ctx pixelgl.Context) {
var err error
va, err = pixelgl.NewVertexArray(
pixelgl.ContextHolder{Context: ctx},
ctx.Shader().VertexFormat(),
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len(vertices),
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indices,
)
if err != nil {
panic(errors.Wrap(err, "failed to create multishape"))
}
})
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va.SetVertices(vertices)
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return &MultiShape{NewShape(parent, picture, color.White, Position(0), va)}
}
// Sprite is a picture that can be drawn on the screen. Optionally it can be color masked
// or tranformed.
//
// Usually, you only transform objects when you're drawing them (by passing transforms to the
// Draw method). With sprites however, it can be useful to also transform them "statically". For
// example, sprites are anchor by their bottom-left corner by default. Setting a transform can
// change this anchored to the center, or wherever you want.
type Sprite struct {
*Shape
}
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// NewSprite creates a new sprite with the supplied picture. The sprite's size is the size of
// the supplied picture. If you want to change the sprite's size, change it's transform.
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func NewSprite(parent pixelgl.Doer, picture *Picture) *Sprite {
var va *pixelgl.VertexArray
parent.Do(func(ctx pixelgl.Context) {
var err error
va, err = pixelgl.NewVertexArray(
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pixelgl.ContextHolder{Context: ctx},
ctx.Shader().VertexFormat(),
4,
[]int{0, 1, 2, 0, 2, 3},
)
if err != nil {
panic(errors.Wrap(err, "failed to create sprite"))
}
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})
vertices := make([]map[pixelgl.Attr]interface{}, 4)
w, h := picture.Bounds().Size.XY()
for i, p := range []Vec{V(0, 0), V(w, 0), V(w, h), V(0, h)} {
texCoord := V(
(picture.Bounds().X()+p.X())/float64(picture.Texture().Width()),
(picture.Bounds().Y()+p.Y())/float64(picture.Texture().Height()),
)
vertices[i] = map[pixelgl.Attr]interface{}{
positionVec2: mgl32.Vec2{float32(p.X()), float32(p.Y())},
colorVec4: mgl32.Vec4{1, 1, 1, 1},
texCoordVec2: mgl32.Vec2{float32(texCoord.X()), float32(texCoord.Y())},
}
}
va.SetVertices(vertices)
return &Sprite{NewShape(parent, picture, color.White, Position(0), va)}
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}
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// LineColor a line shape (with sharp ends) filled with a single color.
type LineColor struct {
*Shape
a, b Vec
width float64
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}
// NewLineColor creates a new line shape between points A and B filled with a single color. Parent
// is an object that this shape belongs to, such as a window, or a graphics effect.
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func NewLineColor(parent pixelgl.Doer, c color.Color, a, b Vec, width float64) *LineColor {
var va *pixelgl.VertexArray
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parent.Do(func(ctx pixelgl.Context) {
var err error
va, err = pixelgl.NewVertexArray(
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pixelgl.ContextHolder{Context: ctx},
ctx.Shader().VertexFormat(),
4,
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[]int{0, 1, 2, 1, 2, 3},
)
if err != nil {
panic(errors.Wrap(err, "failed to create line"))
}
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})
vertices := make([]map[pixelgl.Attr]interface{}, 4)
for i := 0; i < 4; i++ {
vertices[i] = map[pixelgl.Attr]interface{}{
colorVec4: mgl32.Vec4{1, 1, 1, 1},
texCoordVec2: mgl32.Vec2{-1, -1},
}
}
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va.SetVertices(vertices)
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lc := &LineColor{NewShape(parent, nil, c, Position(0), va), a, b, width}
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lc.setPoints()
return lc
}
// setPoints updates the vertex array data according to A, B and width.
func (lc *LineColor) setPoints() {
r := (lc.b - lc.a).Unit().Scaled(lc.width / 2).Rotated(math.Pi / 2)
for i, p := range []Vec{lc.a - r, lc.a + r, lc.b - r, lc.b + r} {
lc.va.SetVertexAttr(i, positionVec2, mgl32.Vec2{float32(p.X()), float32(p.Y())})
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}
}
// SetA changes the position of the first endpoint of a line.
func (lc *LineColor) SetA(a Vec) {
lc.a = a
lc.setPoints()
}
// A returns the current position of the first endpoint of a line.
func (lc *LineColor) A() Vec {
return lc.a
}
// SetB changes the position of the second endpoint of a line.
func (lc *LineColor) SetB(b Vec) {
lc.b = b
lc.setPoints()
}
// B returns the current position of the second endpoint of a line.
func (lc *LineColor) B() Vec {
return lc.b
}
// SetWidth changes the width of a line.
func (lc *LineColor) SetWidth(width float64) {
lc.width = width
lc.setPoints()
}
// Width returns the current width of a line.
func (lc *LineColor) Width() float64 {
return lc.width
}
// PolygonColor is a convex polygon shape filled with a single color.
type PolygonColor struct {
*Shape
points []Vec
}
// NewPolygonColor creates a new polygon shape filled with a single color. Parent is an object
// that this shape belongs to, such as a window, or a graphics effect.
func NewPolygonColor(parent pixelgl.Doer, c color.Color, points ...Vec) *PolygonColor {
var va *pixelgl.VertexArray
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var indices []int
for i := 2; i < len(points); i++ {
indices = append(indices, 0, i-1, i)
}
parent.Do(func(ctx pixelgl.Context) {
var err error
va, err = pixelgl.NewVertexArray(
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pixelgl.ContextHolder{Context: ctx},
ctx.Shader().VertexFormat(),
len(points),
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indices,
)
if err != nil {
panic(errors.Wrap(err, "failed to create polygon"))
}
})
vertices := make([]map[pixelgl.Attr]interface{}, len(points))
for i, p := range points {
vertices[i] = map[pixelgl.Attr]interface{}{
positionVec2: mgl32.Vec2{float32(p.X()), float32(p.Y())},
colorVec4: mgl32.Vec4{1, 1, 1, 1},
texCoordVec2: mgl32.Vec2{-1, -1},
}
}
va.SetVertices(vertices)
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return &PolygonColor{NewShape(parent, nil, c, Position(0), va), points}
}
// NumPoints returns the number of points in a polygon.
func (pc *PolygonColor) NumPoints() int {
return len(pc.points)
}
// SetPoint changes the position of a point in a polygon.
//
// If the index is out of range, this function panics.
func (pc *PolygonColor) SetPoint(i int, point Vec) {
pc.points[i] = point
pc.va.SetVertexAttr(i, positionVec2, mgl32.Vec2{float32(point.X()), float32(point.Y())})
}
// Point returns the position of a point in a polygon.
//
// If the index is out of range, this function panics.
func (pc *PolygonColor) Point(i int) Vec {
return pc.points[i]
}
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// EllipseColor is an ellipse shape filled with a single color.
type EllipseColor struct {
*Shape
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radius Vec
fill float64
}
// NewEllipseColor creates a new ellipse shape filled with a single color. Parent is an object
// that this shape belongs to, such as a window, or a graphics effect. Fill should be a number
// between 0 and 1 which specifies how much of the ellipse will be filled (from the outside). The
// value of 1 means that the whole ellipse is filled. The value of 0 means that none of the
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// ellipse is filled (which makes the ellipse invisible).
func NewEllipseColor(parent pixelgl.Doer, c color.Color, radius Vec, fill float64) *EllipseColor {
var va *pixelgl.VertexArray
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const n = 256
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var indices []int
for i := 2; i < (n+1)*2; i++ {
indices = append(indices, i-2, i-1, i)
}
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parent.Do(func(ctx pixelgl.Context) {
var err error
va, err = pixelgl.NewVertexArray(
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pixelgl.ContextHolder{Context: ctx},
ctx.Shader().VertexFormat(),
(n+1)*2,
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indices,
)
if err != nil {
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panic(errors.Wrap(err, "failed to create ellipse"))
}
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})
vertices := make([]map[pixelgl.Attr]interface{}, (n+1)*2)
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for k := 0; k < n+1; k++ {
i, j := k*2, k*2+1
angle := math.Pi * 2 * float64(k%n) / n
vertices[i] = map[pixelgl.Attr]interface{}{
positionVec2: mgl32.Vec2{
float32(math.Cos(angle) * radius.X()),
float32(math.Sin(angle) * radius.Y()),
},
colorVec4: mgl32.Vec4{1, 1, 1, 1},
texCoordVec2: mgl32.Vec2{-1, -1},
}
vertices[j] = map[pixelgl.Attr]interface{}{
positionVec2: mgl32.Vec2{
float32(math.Cos(angle) * radius.X() * (1 - fill)),
float32(math.Sin(angle) * radius.Y() * (1 - fill)),
},
colorVec4: mgl32.Vec4{1, 1, 1, 1},
texCoordVec2: mgl32.Vec2{-1, -1},
}
}
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va.SetVertices(vertices)
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return &EllipseColor{NewShape(parent, nil, c, Position(0), va), radius, fill}
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}
// Radius returns the radius of an ellipse.
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func (ec *EllipseColor) Radius() Vec {
return ec.radius
}
// Fill returns the fill ratio of an ellipse.
func (ec *EllipseColor) Fill() float64 {
return ec.fill
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}