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graphicscommand: Bug fix: Adjust vertices to avoid jaggy

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If vertices are (almost) half-integer values, adjust them to avoid
jaggy.

Fixes #929.
This commit is contained in:
Hajime Hoshi 2019-08-27 22:33:14 +09:00
parent 22c31da6c1
commit 19103dcfeb
1 changed files with 27 additions and 1 deletions
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28
internal/graphicscommand/command.go
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@ -16,6 +16,7 @@ package graphicscommand
import (
"fmt"
"math"
"github.com/hajimehoshi/ebiten/internal/affine"
"github.com/hajimehoshi/ebiten/internal/driver"
@ -171,6 +172,10 @@ func (q *commandQueue) Enqueue(command command) {
q.commands = append(q.commands, command)
}
func fract(x float32) float32 {
return x - float32(math.Floor(float64(x)))
}
// Flush flushes the command queue.
func (q *commandQueue) Flush() {
if q.err != nil {
@ -184,10 +189,31 @@ func (q *commandQueue) Flush() {
}
if theGraphicsDriver.HasHighPrecisionFloat() {
// Adjust texels.
const dstAdjustmentFactor = 1.0 / 256.0
const texelAdjustmentFactor = 1.0 / 512.0
for i := 0; i < q.nvertices/graphics.VertexFloatNum; i++ {
s := q.srcSizes[i]
// Adjust the destination position to avoid jaggy (#929).
// This is not a perfect solution since texels on a texture can take a position on borders
// which can cause jaggy. But adjusting only edges should work in most cases.
// The ideal solution is to fix shaders, but this makes the applications slow by adding 'if'
// branches.
switch f := fract(vs[i*graphics.VertexFloatNum+0]); {
case 0.5-dstAdjustmentFactor <= f && f < 0.5:
vs[i*graphics.VertexFloatNum+0] -= f - (0.5 - dstAdjustmentFactor)
case 0.5 <= f && f < 0.5+dstAdjustmentFactor:
vs[i*graphics.VertexFloatNum+0] += (0.5 + dstAdjustmentFactor) - f
}
switch f := fract(vs[i*graphics.VertexFloatNum+1]); {
case 0.5-dstAdjustmentFactor <= f && f < 0.5:
vs[i*graphics.VertexFloatNum+1] -= f - (0.5 - dstAdjustmentFactor)
case 0.5 <= f && f < 0.5+dstAdjustmentFactor:
vs[i*graphics.VertexFloatNum+1] += (0.5 + dstAdjustmentFactor) - f
}
// Adjust regions not to violate neighborhoods (#317, #558, #724).
vs[i*graphics.VertexFloatNum+6] -= 1.0 / s.width * texelAdjustmentFactor
vs[i*graphics.VertexFloatNum+7] -= 1.0 / s.height * texelAdjustmentFactor
}