From 14bb08c1df8db9ec6c8a05520d4eee67971235d9 Mon Sep 17 00:00:00 2001 From: Dimitri Sokolyuk Date: Thu, 27 Sep 2018 20:03:23 +0200 Subject: mod tidy --- .../golang.org/x/image/vector/raster_floating.go | 220 --------------------- 1 file changed, 220 deletions(-) delete mode 100644 vendor/golang.org/x/image/vector/raster_floating.go (limited to 'vendor/golang.org/x/image/vector/raster_floating.go') diff --git a/vendor/golang.org/x/image/vector/raster_floating.go b/vendor/golang.org/x/image/vector/raster_floating.go deleted file mode 100644 index fd11db1..0000000 --- a/vendor/golang.org/x/image/vector/raster_floating.go +++ /dev/null @@ -1,220 +0,0 @@ -// Copyright 2016 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -package vector - -// This file contains a floating point math implementation of the vector -// graphics rasterizer. - -import ( - "math" -) - -func floatingMax(x, y float32) float32 { - if x > y { - return x - } - return y -} - -func floatingMin(x, y float32) float32 { - if x < y { - return x - } - return y -} - -func floatingFloor(x float32) int32 { return int32(math.Floor(float64(x))) } -func floatingCeil(x float32) int32 { return int32(math.Ceil(float64(x))) } - -func (z *Rasterizer) floatingLineTo(bx, by float32) { - ax, ay := z.penX, z.penY - z.penX, z.penY = bx, by - dir := float32(1) - if ay > by { - dir, ax, ay, bx, by = -1, bx, by, ax, ay - } - // Horizontal line segments yield no change in coverage. Almost horizontal - // segments would yield some change, in ideal math, but the computation - // further below, involving 1 / (by - ay), is unstable in floating point - // math, so we treat the segment as if it was perfectly horizontal. - if by-ay <= 0.000001 { - return - } - dxdy := (bx - ax) / (by - ay) - - x := ax - y := floatingFloor(ay) - yMax := floatingCeil(by) - if yMax > int32(z.size.Y) { - yMax = int32(z.size.Y) - } - width := int32(z.size.X) - - for ; y < yMax; y++ { - dy := floatingMin(float32(y+1), by) - floatingMax(float32(y), ay) - - // The "float32" in expressions like "float32(foo*bar)" here and below - // look redundant, since foo and bar already have type float32, but are - // explicit in order to disable the compiler's Fused Multiply Add (FMA) - // instruction selection, which can improve performance but can result - // in different rounding errors in floating point computations. - // - // This package aims to have bit-exact identical results across all - // GOARCHes, and across pure Go code and assembly, so it disables FMA. - // - // See the discussion at - // https://groups.google.com/d/topic/golang-dev/Sti0bl2xUXQ/discussion - xNext := x + float32(dy*dxdy) - if y < 0 { - x = xNext - continue - } - buf := z.bufF32[y*width:] - d := float32(dy * dir) - x0, x1 := x, xNext - if x > xNext { - x0, x1 = x1, x0 - } - x0i := floatingFloor(x0) - x0Floor := float32(x0i) - x1i := floatingCeil(x1) - x1Ceil := float32(x1i) - - if x1i <= x0i+1 { - xmf := float32(0.5*(x+xNext)) - x0Floor - if i := clamp(x0i+0, width); i < uint(len(buf)) { - buf[i] += d - float32(d*xmf) - } - if i := clamp(x0i+1, width); i < uint(len(buf)) { - buf[i] += float32(d * xmf) - } - } else { - s := 1 / (x1 - x0) - x0f := x0 - x0Floor - oneMinusX0f := 1 - x0f - a0 := float32(0.5 * s * oneMinusX0f * oneMinusX0f) - x1f := x1 - x1Ceil + 1 - am := float32(0.5 * s * x1f * x1f) - - if i := clamp(x0i, width); i < uint(len(buf)) { - buf[i] += float32(d * a0) - } - - if x1i == x0i+2 { - if i := clamp(x0i+1, width); i < uint(len(buf)) { - buf[i] += float32(d * (1 - a0 - am)) - } - } else { - a1 := float32(s * (1.5 - x0f)) - if i := clamp(x0i+1, width); i < uint(len(buf)) { - buf[i] += float32(d * (a1 - a0)) - } - dTimesS := float32(d * s) - for xi := x0i + 2; xi < x1i-1; xi++ { - if i := clamp(xi, width); i < uint(len(buf)) { - buf[i] += dTimesS - } - } - a2 := a1 + float32(s*float32(x1i-x0i-3)) - if i := clamp(x1i-1, width); i < uint(len(buf)) { - buf[i] += float32(d * (1 - a2 - am)) - } - } - - if i := clamp(x1i, width); i < uint(len(buf)) { - buf[i] += float32(d * am) - } - } - - x = xNext - } -} - -const ( - // almost256 scales a floating point value in the range [0, 1] to a uint8 - // value in the range [0x00, 0xff]. - // - // 255 is too small. Floating point math accumulates rounding errors, so a - // fully covered src value that would in ideal math be float32(1) might be - // float32(1-ε), and uint8(255 * (1-ε)) would be 0xfe instead of 0xff. The - // uint8 conversion rounds to zero, not to nearest. - // - // 256 is too big. If we multiplied by 256, below, then a fully covered src - // value of float32(1) would translate to uint8(256 * 1), which can be 0x00 - // instead of the maximal value 0xff. - // - // math.Float32bits(almost256) is 0x437fffff. - almost256 = 255.99998 - - // almost65536 scales a floating point value in the range [0, 1] to a - // uint16 value in the range [0x0000, 0xffff]. - // - // math.Float32bits(almost65536) is 0x477fffff. - almost65536 = almost256 * 256 -) - -func floatingAccumulateOpOver(dst []uint8, src []float32) { - // Sanity check that len(dst) >= len(src). - if len(dst) < len(src) { - return - } - - acc := float32(0) - for i, v := range src { - acc += v - a := acc - if a < 0 { - a = -a - } - if a > 1 { - a = 1 - } - // This algorithm comes from the standard library's image/draw package. - dstA := uint32(dst[i]) * 0x101 - maskA := uint32(almost65536 * a) - outA := dstA*(0xffff-maskA)/0xffff + maskA - dst[i] = uint8(outA >> 8) - } -} - -func floatingAccumulateOpSrc(dst []uint8, src []float32) { - // Sanity check that len(dst) >= len(src). - if len(dst) < len(src) { - return - } - - acc := float32(0) - for i, v := range src { - acc += v - a := acc - if a < 0 { - a = -a - } - if a > 1 { - a = 1 - } - dst[i] = uint8(almost256 * a) - } -} - -func floatingAccumulateMask(dst []uint32, src []float32) { - // Sanity check that len(dst) >= len(src). - if len(dst) < len(src) { - return - } - - acc := float32(0) - for i, v := range src { - acc += v - a := acc - if a < 0 { - a = -a - } - if a > 1 { - a = 1 - } - dst[i] = uint32(almost65536 * a) - } -} -- cgit v1.2.3