mirror of
https://github.com/bloeys/nterm.git
synced 2025-12-29 14:38:19 +00:00
Disable DepthTest when drawing glyphs+move shared glyph draw logic
With depth testing enabled nearby glyphs can z-fight and so some pixels might be discarded before fragment shader even runs, which causes us to see only part of a letter. As such we always draw with blending enabled and depth testing disabled so that any overlaps simply causes the char pixels to show.
This commit is contained in:
bloeys
238
glyphs/glyphs.go
238
glyphs/glyphs.go
@ -68,9 +68,8 @@ func (gr *GlyphRend) DrawTextOpenGLAbs(text string, screenPos *gglm.Vec3, color
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pos := screenPos.Clone()
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advanceF32 := float32(gr.Atlas.Advance)
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lineHeightF32 := float32(gr.Atlas.LineHeight)
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// scale := gglm.NewVec2(advanceF32, lineHeightF32)
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buffIndex := gr.GlyphCount * floatsPerGlyph
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bufIndex := gr.GlyphCount * floatsPerGlyph
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for _, run := range runs {
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@ -91,155 +90,15 @@ func (gr *GlyphRend) DrawTextOpenGLAbs(text string, screenPos *gglm.Vec3, color
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if isLtr {
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for i := 0; i < len(rs); i++ {
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r := rs[i]
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if r == '\n' {
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screenPos.SetY(screenPos.Y() - lineHeightF32)
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pos = screenPos.Clone()
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prevRune = r
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continue
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} else if r == ' ' {
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pos.AddX(advanceF32)
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prevRune = r
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continue
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} else if r == '\t' {
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pos.AddX(advanceF32 * float32(gr.SpacesPerTab))
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prevRune = r
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continue
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}
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var g FontAtlasGlyph
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if i < len(rs)-1 {
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//start or middle of sentence
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g = gr.glyphFromRunes(r, prevRune, rs[i+1])
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} else {
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//Last character
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g = gr.glyphFromRunes(r, prevRune, invalidRune)
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}
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//See: https://developer.apple.com/library/archive/documentation/TextFonts/Conceptual/CocoaTextArchitecture/Art/glyph_metrics_2x.png
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//The uvs coming in make it so that glyphs are sitting on top of the baseline (no descent) and with horizontal bearing applied.
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//So to position correctly we move them down by the descent amount.
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drawPos := *pos
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drawPos.SetX(drawPos.X() + g.BearingX)
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drawPos.SetY(drawPos.Y() - g.Descent)
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//Add the glyph information to the vbo
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//UV
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gr.GlyphVBO[buffIndex+0] = g.U
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gr.GlyphVBO[buffIndex+1] = g.V
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buffIndex += 2
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//UVSize
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gr.GlyphVBO[buffIndex+0] = g.SizeU
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gr.GlyphVBO[buffIndex+1] = g.SizeV
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buffIndex += 2
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//Color
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gr.GlyphVBO[buffIndex+0] = color.R()
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gr.GlyphVBO[buffIndex+1] = color.G()
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gr.GlyphVBO[buffIndex+2] = color.B()
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gr.GlyphVBO[buffIndex+3] = color.A()
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buffIndex += 4
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//Model Pos
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gr.GlyphVBO[buffIndex+0] = drawPos.X()
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gr.GlyphVBO[buffIndex+1] = drawPos.Y()
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gr.GlyphVBO[buffIndex+2] = drawPos.Z()
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buffIndex += 3
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//Model Scale
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gr.GlyphVBO[buffIndex+0] = g.SizeU
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gr.GlyphVBO[buffIndex+1] = g.SizeV
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buffIndex += 2
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gr.GlyphCount++
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pos.AddX(advanceF32)
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//If we fill the buffer we issue a draw call
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if gr.GlyphCount == MaxGlyphsPerBatch {
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gr.Draw()
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buffIndex = 0
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}
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prevRune = r
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gr.drawRune(rs, i, prevRune, screenPos, pos, color, advanceF32, lineHeightF32, &bufIndex, isLtr)
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prevRune = rs[i]
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}
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} else {
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for i := len(rs) - 1; i >= 0; i-- {
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r := rs[i]
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if r == '\n' {
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screenPos.SetY(screenPos.Y() - lineHeightF32)
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pos = screenPos.Clone()
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prevRune = r
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continue
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} else if r == ' ' {
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pos.AddX(advanceF32)
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prevRune = r
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continue
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} else if r == '\t' {
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pos.AddX(advanceF32 * float32(gr.SpacesPerTab))
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prevRune = r
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continue
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}
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var g FontAtlasGlyph
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if i > 0 {
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//start or middle of sentence
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g = gr.glyphFromRunes(r, rs[i-1], prevRune)
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} else {
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//Last character
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g = gr.glyphFromRunes(r, invalidRune, prevRune)
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}
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//See: https://developer.apple.com/library/archive/documentation/TextFonts/Conceptual/CocoaTextArchitecture/Art/glyph_metrics_2x.png
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//The uvs coming in make it so that glyphs are sitting on top of the baseline (no descent) and with horizontal bearing applied.
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//So to position correctly we move them down by the descent amount.
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drawPos := *pos
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drawPos.SetX(drawPos.X() + g.BearingX)
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drawPos.SetY(drawPos.Y() - g.Descent)
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//Add the glyph information to the vbo
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//UV
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gr.GlyphVBO[buffIndex+0] = g.U
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gr.GlyphVBO[buffIndex+1] = g.V
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buffIndex += 2
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//UVSize
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gr.GlyphVBO[buffIndex+0] = g.SizeU
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gr.GlyphVBO[buffIndex+1] = g.SizeV
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buffIndex += 2
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//Color
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gr.GlyphVBO[buffIndex+0] = color.R()
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gr.GlyphVBO[buffIndex+1] = color.G()
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gr.GlyphVBO[buffIndex+2] = color.B()
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gr.GlyphVBO[buffIndex+3] = color.A()
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buffIndex += 4
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//Model Pos
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gr.GlyphVBO[buffIndex+0] = drawPos.X()
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gr.GlyphVBO[buffIndex+1] = drawPos.Y()
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gr.GlyphVBO[buffIndex+2] = drawPos.Z()
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buffIndex += 3
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//Model Scale
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gr.GlyphVBO[buffIndex+0] = g.SizeU
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gr.GlyphVBO[buffIndex+1] = g.SizeV
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buffIndex += 2
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gr.GlyphCount++
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pos.AddX(advanceF32)
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//If we fill the buffer we issue a draw call
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if gr.GlyphCount == MaxGlyphsPerBatch {
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gr.Draw()
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buffIndex = 0
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}
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prevRune = r
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gr.drawRune(rs, i, prevRune, screenPos, pos, color, advanceF32, lineHeightF32, &bufIndex, isLtr)
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prevRune = rs[i]
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}
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}
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@ -247,8 +106,92 @@ func (gr *GlyphRend) DrawTextOpenGLAbs(text string, screenPos *gglm.Vec3, color
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}
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}
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func (gr *GlyphRend) drawRune(rs []rune, i int, prevRune rune, screenPos, pos *gglm.Vec3, color *gglm.Vec4, advanceF32, lineHeightF32 float32, bufIndex *uint32, isLtr bool) {
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r := rs[i]
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if r == '\n' {
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screenPos.SetY(screenPos.Y() - lineHeightF32)
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*pos = *screenPos.Clone()
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// prevRune = r
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return
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} else if r == ' ' {
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pos.AddX(advanceF32)
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// prevRune = r
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return
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} else if r == '\t' {
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pos.AddX(advanceF32 * float32(gr.SpacesPerTab))
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// prevRune = r
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return
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}
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var g FontAtlasGlyph
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if isLtr {
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if i < len(rs)-1 {
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//start or middle of sentence
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g = gr.glyphFromRunes(r, prevRune, rs[i+1])
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} else {
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//Last character
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g = gr.glyphFromRunes(r, prevRune, invalidRune)
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}
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} else {
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if i > 0 {
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//start or middle of sentence
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g = gr.glyphFromRunes(r, rs[i-1], prevRune)
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} else {
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//Last character
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g = gr.glyphFromRunes(r, invalidRune, prevRune)
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}
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}
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//We must adjust char positioning according to: https://developer.apple.com/library/archive/documentation/TextFonts/Conceptual/CocoaTextArchitecture/Art/glyph_metrics_2x.png
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drawPos := *pos
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drawPos.SetX(drawPos.X() + g.BearingX)
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drawPos.SetY(drawPos.Y() - g.Descent)
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//Add the glyph information to the vbo
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//UV
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gr.GlyphVBO[*bufIndex+0] = g.U
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gr.GlyphVBO[*bufIndex+1] = g.V
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*bufIndex += 2
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//UVSize
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gr.GlyphVBO[*bufIndex+0] = g.SizeU
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gr.GlyphVBO[*bufIndex+1] = g.SizeV
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*bufIndex += 2
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//Color
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gr.GlyphVBO[*bufIndex+0] = color.R()
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gr.GlyphVBO[*bufIndex+1] = color.G()
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gr.GlyphVBO[*bufIndex+2] = color.B()
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gr.GlyphVBO[*bufIndex+3] = color.A()
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*bufIndex += 4
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//Model Pos
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gr.GlyphVBO[*bufIndex+0] = drawPos.X()
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gr.GlyphVBO[*bufIndex+1] = drawPos.Y()
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gr.GlyphVBO[*bufIndex+2] = drawPos.Z()
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*bufIndex += 3
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//Model Scale
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gr.GlyphVBO[*bufIndex+0] = g.SizeU
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gr.GlyphVBO[*bufIndex+1] = g.SizeV
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*bufIndex += 2
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gr.GlyphCount++
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pos.AddX(advanceF32)
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//If we fill the buffer we issue a draw call
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if gr.GlyphCount == MaxGlyphsPerBatch {
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gr.Draw()
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*bufIndex = 0
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}
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// prevRune = r
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}
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func (gr *GlyphRend) GetTextRuns(t string) [][]rune {
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//PERF: Might be better to pass a [][]rune buffer to avoid allocating on the heap
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rs := []rune(t)
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if len(rs) == 0 {
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@ -405,7 +348,10 @@ func (gr *GlyphRend) Draw() {
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gr.InstancedBuf.Bind()
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gr.GlyphMat.Bind()
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//We need to disable depth testing so that nearby characters don't occlude each other
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gl.Disable(gl.DEPTH_TEST)
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gl.DrawElementsInstanced(gl.TRIANGLES, gr.GlyphMesh.Buf.IndexBufCount, gl.UNSIGNED_INT, gl.PtrOffset(0), int32(gr.GlyphCount))
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gl.Enable(gl.DEPTH_TEST)
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gr.GlyphCount = 0
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}
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