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ui/app/internal/gpu: replace look up texture with calculation

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Signed-off-by: Elias Naur <mail@eliasnaur.com>
This commit is contained in:
Elias Naur
2019-06-10 01:11:19 +02:00
parent 8917cb33bc
commit 1f809234b8
2 changed files with 13 additions and 115 deletions
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ui/app/internal/gpu/path.go
+13 -39
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@@ -48,7 +48,6 @@ type stenciler struct {
uIntersectUVOffset gl.Uniform
uIntersectUVScale gl.Uniform
indexBuf gl.Buffer
areaLUT gl.Texture
}
type fboSet struct {
@@ -122,13 +121,7 @@ func newStenciler(ctx *context) *stenciler {
if err != nil {
panic(err)
}
uAreaLUT := gl.GetUniformLocation(ctx.Functions, prog, "areaLUT")
ctx.UseProgram(prog)
ctx.Uniform1i(uAreaLUT, 0)
areaLUT, err := loadLUT(ctx, genAreaLUT(256, 256))
if err != nil {
panic(err)
}
iprog, err := gl.CreateProgram(ctx.Functions, intersectVSrc, intersectFSrc, intersectAttribs)
if err != nil {
panic(err)
@@ -141,7 +134,6 @@ func newStenciler(ctx *context) *stenciler {
defFBO: defFBO,
prog: prog,
iprog: iprog,
areaLUT: areaLUT,
uScale: gl.GetUniformLocation(ctx.Functions, prog, "scale"),
uOffset: gl.GetUniformLocation(ctx.Functions, prog, "offset"),
uPathOffset: gl.GetUniformLocation(ctx.Functions, prog, "pathOffset"),
@@ -205,7 +197,6 @@ func (s *fboSet) delete(ctx *context, idx int) {
func (s *stenciler) release() {
s.fbos.delete(s.ctx, 0)
s.ctx.DeleteTexture(s.areaLUT)
s.ctx.DeleteProgram(s.prog)
s.ctx.DeleteBuffer(s.indexBuf)
}
@@ -281,7 +272,6 @@ func (s *stenciler) begin(sizes []image.Point) {
s.ctx.BlendFunc(gl.ONE, gl.ONE)
s.fbos.resize(s.ctx, sizes)
s.ctx.ClearColor(0.0, 0.0, 0.0, 0.0)
s.ctx.BindTexture(gl.TEXTURE_2D, s.areaLUT)
s.ctx.UseProgram(s.prog)
s.ctx.EnableVertexAttribArray(attribPathCorner)
s.ctx.EnableVertexAttribArray(attribPathMaxY)
@@ -365,23 +355,6 @@ func (c *coverer) cover(z float32, mat materialType, col [4]float32, scale, off,
c.ctx.DrawArrays(gl.TRIANGLE_STRIP, 0, 4)
}
func loadLUT(ctx *context, lut *image.Gray) (gl.Texture, error) {
tex := ctx.CreateTexture()
ctx.BindTexture(gl.TEXTURE_2D, tex)
ctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
ctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
ctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
ctx.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
ctx.PixelStorei(gl.UNPACK_ALIGNMENT, 1)
if lut.Stride != lut.Bounds().Dx() {
panic("unsupported LUT stride")
}
tt := ctx.caps.alphaTriple
ctx.TexImage2D(gl.TEXTURE_2D, 0, tt.internalFormat, lut.Bounds().Dx(), lut.Bounds().Dy(), tt.format, tt.typ, lut.Pix)
ctx.PixelStorei(gl.UNPACK_ALIGNMENT, 4)
return tex, nil
}
const stencilVSrc = `
#version 100
@@ -494,19 +467,20 @@ void main() {
// And the slope.
vec2 d_half = mix(p1, v, t);
float dy = d_half.y/d_half.x;
// Together, y and dy form a line approximation. The areaLUT table
// maps the line to a pixel coverage.
// Together, y and dy form a line approximation.
// Compute the fragment area above the line.
// The area is symmetric around dy = 0. Scale slope with extent width.
float width = extent.y - extent.x;
// The first axis maps y in [-8;+8] to [0;1].
float areau = y/16.0 + 0.5;
// The second axis maps slopes in [0;16] to [0;1]. The area is symmetric
// around dy = 0. Scale slope with extent width.
float areav = abs(dy*width)/16.0;
// Look up coverage from y and slope and scale to extent.
float cover = texture2D(areaLUT, vec2(areau, areav)).r*width;
if (width == 0.0)
cover = 0.0; // Needed on the iOS simulator.
gl_FragColor.r = cover;
dy = abs(dy*width);
vec4 sides = vec4(dy*+0.5 + y, dy*-0.5 + y, (+0.5-y)/dy, (-0.5-y)/dy);
sides = clamp(sides+0.5, 0.0, 1.0);
float area = 0.5*(sides.z - sides.z*sides.y + 1.0 - sides.x+sides.x*sides.w);
area *= width;
gl_FragColor.r = area;
}
`