forked from faiface/pixel
/
canvas.go
370 lines (316 loc) · 9.22 KB
/
canvas.go
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package pixelgl
import (
"fmt"
"image/color"
"github.com/faiface/glhf"
"github.com/faiface/mainthread"
"github.com/faiface/pixel"
"github.com/go-gl/mathgl/mgl32"
"github.com/pkg/errors"
)
// Canvas is an off-screen rectangular BasicTarget and Picture at the same time, that you can draw
// onto.
//
// It supports TrianglesPosition, TrianglesColor, TrianglesPicture and PictureColor.
type Canvas struct {
gf *GLFrame
shader *glShader
cmp pixel.ComposeMethod
mat mgl32.Mat3
col mgl32.Vec4
smooth bool
sprite *pixel.Sprite
}
var _ pixel.ComposeTarget = (*Canvas)(nil)
// NewCanvas creates a new empty, fully transparent Canvas with given bounds.
func NewCanvas(bounds pixel.Rect) *Canvas {
c := &Canvas{
gf: NewGLFrame(bounds),
mat: mgl32.Ident3(),
col: mgl32.Vec4{1, 1, 1, 1},
}
baseShader(c)
c.SetBounds(bounds)
c.shader.update()
return c
}
// SetUniform will update the named uniform with the value of any supported underlying
// attribute variable. If the uniform already exists, including defaults, they will be reassigned
// to the new value. The value can be a pointer.
func (c *Canvas) SetUniform(name string, value interface{}) {
c.shader.setUniform(name, value)
}
// SetFragmentShader allows you to set a new fragment shader on the underlying
// framebuffer. Argument "src" is the GLSL source, not a filename.
func (c *Canvas) SetFragmentShader(src string) {
c.shader.fs = src
c.shader.update()
}
// MakeTriangles creates a specialized copy of the supplied Triangles that draws onto this Canvas.
//
// TrianglesPosition, TrianglesColor and TrianglesPicture are supported.
func (c *Canvas) MakeTriangles(t pixel.Triangles) pixel.TargetTriangles {
return &canvasTriangles{
GLTriangles: NewGLTriangles(c.shader.s, t),
dst: c,
}
}
// MakePicture create a specialized copy of the supplied Picture that draws onto this Canvas.
//
// PictureColor is supported.
func (c *Canvas) MakePicture(p pixel.Picture) pixel.TargetPicture {
if cp, ok := p.(*canvasPicture); ok {
return &canvasPicture{
GLPicture: cp.GLPicture,
dst: c,
}
}
if gp, ok := p.(GLPicture); ok {
return &canvasPicture{
GLPicture: gp,
dst: c,
}
}
return &canvasPicture{
GLPicture: NewGLPicture(p),
dst: c,
}
}
// SetMatrix sets a Matrix that every point will be projected by.
func (c *Canvas) SetMatrix(m pixel.Matrix) {
// pixel.Matrix is 3x2 with an implicit 0, 0, 1 row after it. So
// [0] [2] [4] [0] [3] [6]
// [1] [3] [5] => [1] [4] [7]
// 0 0 1 0 0 1
// since all matrix ops are affine, the last row never changes, and we don't need to copy it
for i, j := range [...]int{0, 1, 3, 4, 6, 7} {
c.mat[j] = float32(m[i])
}
}
// SetColorMask sets a color that every color in triangles or a picture will be multiplied by.
func (c *Canvas) SetColorMask(col color.Color) {
rgba := pixel.Alpha(1)
if col != nil {
rgba = pixel.ToRGBA(col)
}
c.col = mgl32.Vec4{
float32(rgba.R),
float32(rgba.G),
float32(rgba.B),
float32(rgba.A),
}
}
// SetComposeMethod sets a Porter-Duff composition method to be used in the following draws onto
// this Canvas.
func (c *Canvas) SetComposeMethod(cmp pixel.ComposeMethod) {
c.cmp = cmp
}
// SetBounds resizes the Canvas to the new bounds. Old content will be preserved.
func (c *Canvas) SetBounds(bounds pixel.Rect) {
c.gf.SetBounds(bounds)
if c.sprite == nil {
c.sprite = pixel.NewSprite(nil, pixel.Rect{})
}
c.sprite.Set(c, c.Bounds())
//c.sprite.SetMatrix(pixel.IM.Moved(c.Bounds().Center()))
}
// Bounds returns the rectangular bounds of the Canvas.
func (c *Canvas) Bounds() pixel.Rect {
return c.gf.Bounds()
}
// SetSmooth sets whether stretched Pictures drawn onto this Canvas should be drawn smooth or
// pixely.
func (c *Canvas) SetSmooth(smooth bool) {
c.smooth = smooth
}
// Smooth returns whether stretched Pictures drawn onto this Canvas are set to be drawn smooth or
// pixely.
func (c *Canvas) Smooth() bool {
return c.smooth
}
// must be manually called inside mainthread
func (c *Canvas) setGlhfBounds() {
_, _, bw, bh := intBounds(c.gf.Bounds())
glhf.Bounds(0, 0, bw, bh)
}
// must be manually called inside mainthread
func setBlendFunc(cmp pixel.ComposeMethod) {
switch cmp {
case pixel.ComposeOver:
glhf.BlendFunc(glhf.One, glhf.OneMinusSrcAlpha)
case pixel.ComposeIn:
glhf.BlendFunc(glhf.DstAlpha, glhf.Zero)
case pixel.ComposeOut:
glhf.BlendFunc(glhf.OneMinusDstAlpha, glhf.Zero)
case pixel.ComposeAtop:
glhf.BlendFunc(glhf.DstAlpha, glhf.OneMinusSrcAlpha)
case pixel.ComposeRover:
glhf.BlendFunc(glhf.OneMinusDstAlpha, glhf.One)
case pixel.ComposeRin:
glhf.BlendFunc(glhf.Zero, glhf.SrcAlpha)
case pixel.ComposeRout:
glhf.BlendFunc(glhf.Zero, glhf.OneMinusSrcAlpha)
case pixel.ComposeRatop:
glhf.BlendFunc(glhf.OneMinusDstAlpha, glhf.SrcAlpha)
case pixel.ComposeXor:
glhf.BlendFunc(glhf.OneMinusDstAlpha, glhf.OneMinusSrcAlpha)
case pixel.ComposePlus:
glhf.BlendFunc(glhf.One, glhf.One)
case pixel.ComposeCopy:
glhf.BlendFunc(glhf.One, glhf.Zero)
default:
panic(errors.New("Canvas: invalid compose method"))
}
}
// Clear fills the whole Canvas with a single color.
func (c *Canvas) Clear(color color.Color) {
c.gf.Dirty()
rgba := pixel.ToRGBA(color)
// color masking
rgba = rgba.Mul(pixel.RGBA{
R: float64(c.col[0]),
G: float64(c.col[1]),
B: float64(c.col[2]),
A: float64(c.col[3]),
})
mainthread.CallNonBlock(func() {
c.setGlhfBounds()
c.gf.Frame().Begin()
glhf.Clear(
float32(rgba.R),
float32(rgba.G),
float32(rgba.B),
float32(rgba.A),
)
c.gf.Frame().End()
})
}
// Color returns the color of the pixel over the given position inside the Canvas.
func (c *Canvas) Color(at pixel.Vec) pixel.RGBA {
return c.gf.Color(at)
}
// Texture returns the underlying OpenGL Texture of this Canvas.
//
// Implements GLPicture interface.
func (c *Canvas) Texture() *glhf.Texture {
return c.gf.Texture()
}
// Frame returns the underlying OpenGL Frame of this Canvas.
func (c *Canvas) Frame() *glhf.Frame {
return c.gf.frame
}
// SetPixels replaces the content of the Canvas with the provided pixels. The provided slice must be
// an alpha-premultiplied RGBA sequence of correct length (4 * width * height).
func (c *Canvas) SetPixels(pixels []uint8) {
c.gf.Dirty()
mainthread.Call(func() {
tex := c.Texture()
tex.Begin()
tex.SetPixels(0, 0, tex.Width(), tex.Height(), pixels)
tex.End()
})
}
// Pixels returns an alpha-premultiplied RGBA sequence of the content of the Canvas.
func (c *Canvas) Pixels() []uint8 {
var pixels []uint8
mainthread.Call(func() {
tex := c.Texture()
tex.Begin()
pixels = tex.Pixels(0, 0, tex.Width(), tex.Height())
tex.End()
})
return pixels
}
// Draw draws the content of the Canvas onto another Target, transformed by the given Matrix, just
// like if it was a Sprite containing the whole Canvas.
func (c *Canvas) Draw(t pixel.Target, matrix pixel.Matrix) {
c.sprite.Draw(t, matrix)
}
// DrawColorMask draws the content of the Canvas onto another Target, transformed by the given
// Matrix and multiplied by the given mask, just like if it was a Sprite containing the whole Canvas.
//
// If the color mask is nil, a fully opaque white mask will be used causing no effect.
func (c *Canvas) DrawColorMask(t pixel.Target, matrix pixel.Matrix, mask color.Color) {
c.sprite.DrawColorMask(t, matrix, mask)
}
type canvasTriangles struct {
*GLTriangles
dst *Canvas
}
func (ct *canvasTriangles) draw(tex *glhf.Texture, bounds pixel.Rect) {
ct.dst.gf.Dirty()
// save the current state vars to avoid race condition
cmp := ct.dst.cmp
smt := ct.dst.smooth
mat := ct.dst.mat
col := ct.dst.col
mainthread.CallNonBlock(func() {
ct.dst.setGlhfBounds()
setBlendFunc(cmp)
frame := ct.dst.gf.Frame()
shader := ct.dst.shader.s
frame.Begin()
shader.Begin()
ct.dst.shader.uniformDefaults.transform = mat
ct.dst.shader.uniformDefaults.colormask = col
dstBounds := ct.dst.Bounds()
ct.dst.shader.uniformDefaults.bounds = mgl32.Vec4{
float32(dstBounds.Min.X),
float32(dstBounds.Min.Y),
float32(dstBounds.W()),
float32(dstBounds.H()),
}
bx, by, bw, bh := intBounds(bounds)
ct.dst.shader.uniformDefaults.texbounds = mgl32.Vec4{
float32(bx),
float32(by),
float32(bw),
float32(bh),
}
for loc, u := range ct.dst.shader.uniforms {
ct.dst.shader.s.SetUniformAttr(loc, u.Value())
}
if tex == nil {
ct.vs.Begin()
ct.vs.Draw()
ct.vs.End()
} else {
tex.Begin()
if tex.Smooth() != smt {
tex.SetSmooth(smt)
}
ct.vs.Begin()
ct.vs.Draw()
ct.vs.End()
tex.End()
}
shader.End()
frame.End()
})
}
func (ct *canvasTriangles) Draw() {
ct.draw(nil, pixel.Rect{})
}
type canvasPicture struct {
GLPicture
dst *Canvas
}
func (cp *canvasPicture) Draw(t pixel.TargetTriangles) {
ct := t.(*canvasTriangles)
if cp.dst != ct.dst {
panic(fmt.Errorf("(%T).Draw: TargetTriangles generated by different Canvas", cp))
}
ct.draw(cp.GLPicture.Texture(), cp.GLPicture.Bounds())
}
const (
canvasPosition int = iota
canvasColor
canvasTexCoords
canvasIntensity
)
var defaultCanvasVertexFormat = glhf.AttrFormat{
canvasPosition: {Name: "aPosition", Type: glhf.Vec2},
canvasColor: {Name: "aColor", Type: glhf.Vec4},
canvasTexCoords: {Name: "aTexCoords", Type: glhf.Vec2},
canvasIntensity: {Name: "aIntensity", Type: glhf.Float},
}