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Abstract glyph renderer
This commit is contained in:
bloeys
297
glyphs/glyphs.go
Executable file
297
glyphs/glyphs.go
Executable file
@ -0,0 +1,297 @@
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package glyphs
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import (
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"math/rand"
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"os"
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"unicode"
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"github.com/bloeys/gglm/gglm"
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"github.com/bloeys/nmage/assets"
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"github.com/bloeys/nmage/buffers"
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"github.com/bloeys/nmage/materials"
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"github.com/bloeys/nmage/meshes"
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"github.com/go-gl/gl/v4.1-core/gl"
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"github.com/golang/freetype/truetype"
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)
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type GlyphRend struct {
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Atlas *FontAtlas
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AtlasTex *assets.Texture
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GlyphMesh *meshes.Mesh
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InstancedBuf buffers.Buffer
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GlyphMat *materials.Material
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GlyphCount int32
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GlyphVBO []float32
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}
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//getGlyphRanges returns a list of ranges, each range is: [i][0]<=range<[i][1]
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func getGlyphRanges(f *truetype.Font) (ret [][2]rune) {
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rr := [2]rune{-1, -1}
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for r := rune(0); r <= unicode.MaxRune; r++ {
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if privateUseArea(r) {
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continue
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}
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if f.Index(r) == 0 {
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continue
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}
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if rr[1] == r {
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rr[1] = r + 1
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continue
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}
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if rr[0] != -1 {
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ret = append(ret, rr)
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}
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rr = [2]rune{r, r + 1}
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}
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if rr[0] != -1 {
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ret = append(ret, rr)
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}
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return ret
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}
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func privateUseArea(r rune) bool {
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return 0xe000 <= r && r <= 0xf8ff ||
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0xf0000 <= r && r <= 0xffffd ||
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0x100000 <= r && r <= 0x10fffd
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}
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//getGlyphsFromRanges takes ranges of runes and produces an array of all the runes in these ranges
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func getGlyphsFromRanges(ranges [][2]rune) []rune {
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out := make([]rune, 0)
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for _, rr := range ranges {
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temp := make([]rune, 0, rr[1]-rr[0])
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for r := rr[0]; r < rr[1]; r++ {
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temp = append(temp, r)
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}
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out = append(out, temp...)
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}
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return out
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}
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func (gr *GlyphRend) DrawTextOpenGL(text string, startPos *gglm.Vec3, winWidth, winHeight int32) {
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//The projection matrix fits the screen size. This is needed so we can size and position characters correctly.
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projMtx := gglm.Ortho(0, float32(winWidth), float32(winHeight), 0, 0.1, 10)
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viewMtx := gglm.LookAt(gglm.NewVec3(0, 0, -1), gglm.NewVec3(0, 0, 0), gglm.NewVec3(0, 1, 0))
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projViewMtx := projMtx.Clone().Mul(viewMtx)
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gr.GlyphMat.DiffuseTex = gr.AtlasTex.TexID
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gr.GlyphMat.SetUnifMat4("projViewMat", &projViewMtx.Mat4)
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gr.GlyphMat.Bind()
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//Prepass to pre-allocate the buffer
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rs := []rune(text)
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const floatsPerGlyph = 18
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rCol := rand.Float32()
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gCol := rand.Float32()
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bCol := rand.Float32()
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pos := startPos.Clone()
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instancedData := make([]float32, 0, len(rs)*floatsPerGlyph) //This a larger approximation than needed because we don't count spaces etc
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for i := 0; i < len(rs); i++ {
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r := rs[i]
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g := gr.Atlas.Glyphs[r]
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if r == '\n' {
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startPos.SetY(startPos.Y() - float32(gr.Atlas.LineHeight))
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pos = startPos.Clone()
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continue
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}
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gr.GlyphCount++
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height := float32(g.Ascent + g.Descent)
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scale := gglm.NewVec3(g.Advance, height, 1)
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//See: https://developer.apple.com/library/archive/documentation/TextFonts/Conceptual/CocoaTextArchitecture/Art/glyph_metrics_2x.png
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//Quads are drawn from the center and so that's our baseline. But chars shouldn't be centered, they should follow ascent/decent/advance.
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//To make them do that vertically, we raise them above the baseline (y+height/2), then since they are sitting on top of the baseline we can simply
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//move them down by the decent amount to put them in the correct vertical position.
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//
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//Horizontally the character should be drawn from the left edge not the center, so we just move it forward by advance/2
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drawPos := *pos
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drawPos.SetX(drawPos.X() + g.Advance*0.5)
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drawPos.SetY(drawPos.Y() + height*0.5 - g.Descent)
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instancedData = append(instancedData, []float32{
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g.U, g.V,
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g.U + g.SizeU, g.V,
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g.U, g.V + g.SizeV,
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g.U + g.SizeU, g.V + g.SizeV,
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rCol, gCol, bCol, 1, //Color
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drawPos.X(), drawPos.Y(), drawPos.Z(), //Model pos
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scale.X(), scale.Y(), scale.Z(), //Model scale
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}...)
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pos.SetX(pos.X() + g.Advance)
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}
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gr.GlyphVBO = append(gr.GlyphVBO, instancedData...)
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}
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func (gr *GlyphRend) Draw() {
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gr.InstancedBuf.SetData(gr.GlyphVBO)
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gr.InstancedBuf.Bind()
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gr.GlyphMat.Bind()
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gl.DrawElementsInstanced(gl.TRIANGLES, gr.GlyphMesh.Buf.IndexBufCount, gl.UNSIGNED_INT, gl.PtrOffset(0), gr.GlyphCount)
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gr.InstancedBuf.UnBind()
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gr.GlyphCount = 0
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gr.GlyphVBO = []float32{}
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}
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func (gr *GlyphRend) SetFace(fontOptions *truetype.Options) {
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face := truetype.NewFace(gr.Atlas.Font, fontOptions)
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gr.Atlas = NewFontAtlasFromFont(gr.Atlas.Font, face, uint(fontOptions.Size))
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}
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func (gr *GlyphRend) SetFontFromFile(fontFile string, fontOptions *truetype.Options) error {
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atlas, err := NewFontAtlasFromFile(fontFile, fontOptions)
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if err != nil {
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return err
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}
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gr.Atlas = atlas
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return nil
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}
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func NewGlyphRend(fontFile string, fontOptions *truetype.Options) (*GlyphRend, error) {
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atlas, err := NewFontAtlasFromFile(fontFile, fontOptions)
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if err != nil {
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return nil, err
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}
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//Create OpenGL texture
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pngFileName := fontFile + "atlas.png"
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err = SaveImgToPNG(atlas.Img, pngFileName)
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if err != nil {
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return nil, err
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}
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atlasTex, err := assets.LoadPNGTexture(pngFileName)
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if err != nil {
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return nil, err
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}
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os.Remove(pngFileName)
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gl.BindTexture(gl.TEXTURE_2D, atlasTex.TexID)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
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gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
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gl.BindTexture(gl.TEXTURE_2D, 0)
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//Create glyph mesh
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glyphMesh := &meshes.Mesh{
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Name: "glypQuad",
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//VertPos, UV, Color; Instanced attributes are stored separately
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Buf: buffers.NewBuffer(
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buffers.Element{ElementType: buffers.DataTypeVec3},
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),
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}
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glyphMesh.Buf.SetData([]float32{
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-0.5, -0.5, 0,
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0.5, -0.5, 0,
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-0.5, 0.5, 0,
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0.5, 0.5, 0,
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})
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glyphMesh.Buf.SetIndexBufData([]uint32{
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0, 1, 2,
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1, 3, 2,
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})
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//Setup material
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glyphMat := materials.NewMaterial("glyphMat", "./res/shaders/glyph")
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glyphMat.SetAttribute(glyphMesh.Buf)
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//Create instanced buf and set its instanced attributes.
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//Multiple VBOs under one VAO, one VBO for vertex data, and one VBO for instanced data.
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instancedBuf := buffers.Buffer{
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VAOID: glyphMesh.Buf.VAOID,
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}
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instancedBuf.SetLayout(
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buffers.Element{ElementType: buffers.DataTypeVec2}, //UVST0
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buffers.Element{ElementType: buffers.DataTypeVec2}, //UVST1
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buffers.Element{ElementType: buffers.DataTypeVec2}, //UVST2
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buffers.Element{ElementType: buffers.DataTypeVec2}, //UVST3
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buffers.Element{ElementType: buffers.DataTypeVec4}, //Color
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buffers.Element{ElementType: buffers.DataTypeVec3}, //ModelPos
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buffers.Element{ElementType: buffers.DataTypeVec3}, //ModelScale
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)
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gl.GenBuffers(1, &instancedBuf.BufID)
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if instancedBuf.BufID == 0 {
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panic("Failed to create openGL buffer")
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}
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instancedBuf.Bind()
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gl.BindBuffer(gl.ARRAY_BUFFER, instancedBuf.BufID)
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layout := instancedBuf.GetLayout()
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//4 UV values
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uvEle := layout[0]
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gl.EnableVertexAttribArray(1)
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gl.VertexAttribPointer(1, uvEle.ElementType.CompCount(), uvEle.ElementType.GLType(), false, instancedBuf.Stride, gl.PtrOffset(uvEle.Offset))
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gl.VertexAttribDivisor(1, 1)
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uvEle = layout[1]
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gl.EnableVertexAttribArray(2)
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gl.VertexAttribPointer(2, uvEle.ElementType.CompCount(), uvEle.ElementType.GLType(), false, instancedBuf.Stride, gl.PtrOffset(uvEle.Offset))
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gl.VertexAttribDivisor(2, 1)
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uvEle = layout[2]
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gl.EnableVertexAttribArray(3)
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gl.VertexAttribPointer(3, uvEle.ElementType.CompCount(), uvEle.ElementType.GLType(), false, instancedBuf.Stride, gl.PtrOffset(uvEle.Offset))
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gl.VertexAttribDivisor(3, 1)
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uvEle = layout[3]
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gl.EnableVertexAttribArray(4)
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gl.VertexAttribPointer(4, uvEle.ElementType.CompCount(), uvEle.ElementType.GLType(), false, instancedBuf.Stride, gl.PtrOffset(uvEle.Offset))
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gl.VertexAttribDivisor(4, 1)
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//Rest of instanced attributes
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colorEle := layout[4]
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gl.EnableVertexAttribArray(5)
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gl.VertexAttribPointer(5, colorEle.ElementType.CompCount(), colorEle.ElementType.GLType(), false, instancedBuf.Stride, gl.PtrOffset(colorEle.Offset))
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gl.VertexAttribDivisor(5, 1)
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posEle := layout[5]
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gl.EnableVertexAttribArray(6)
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gl.VertexAttribPointer(6, posEle.ElementType.CompCount(), posEle.ElementType.GLType(), false, instancedBuf.Stride, gl.PtrOffset(posEle.Offset))
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gl.VertexAttribDivisor(6, 1)
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scaleEle := layout[6]
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gl.EnableVertexAttribArray(7)
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gl.VertexAttribPointer(7, scaleEle.ElementType.CompCount(), scaleEle.ElementType.GLType(), false, instancedBuf.Stride, gl.PtrOffset(scaleEle.Offset))
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gl.VertexAttribDivisor(7, 1)
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gl.BindBuffer(gl.ARRAY_BUFFER, 0)
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instancedBuf.UnBind()
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return &GlyphRend{
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Atlas: atlas,
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AtlasTex: &atlasTex,
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GlyphMesh: glyphMesh,
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InstancedBuf: instancedBuf,
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GlyphMat: glyphMat,
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GlyphCount: 0,
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GlyphVBO: make([]float32, 0),
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}, nil
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}
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