151 lines
4.2 KiB
Go
151 lines
4.2 KiB
Go
//go:build gl
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package render
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import (
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"unsafe"
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"mc/internal/mesh"
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"github.com/go-gl/gl/v3.3-core/gl"
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)
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// chunkKey 区块坐标 → key（与 world 包一致）。
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func chunkKey(cx, cz int32) uint64 { return uint64(uint32(cx))<<32 | uint64(uint32(cz)) }
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// UploadChunk 上传区块网格到 GPU（dirty 网格重建后调用，渲染.md §3.3）。
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// 三类网格合并为单 VBO + 单 IBO：不透明 → cutout → 半透明 顺序连续存放。
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func (r *Renderer) UploadChunk(cx, cz int32, m *mesh.ChunkMesh) {
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k := chunkKey(cx, cz)
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if old, ok := r.chunks[k]; ok {
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old.destroy()
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}
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cg := &chunkGL{}
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gl.GenVertexArrays(1, &cg.vao)
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gl.GenBuffers(1, &cg.vbo)
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gl.GenBuffers(1, &cg.ibo)
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gl.BindVertexArray(cg.vao)
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// 合并顶点
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all := make([]mesh.Vertex, 0, len(m.Opaque)+len(m.Cutout)+len(m.Translucent))
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all = append(all, m.Opaque...)
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all = append(all, m.Cutout...)
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all = append(all, m.Translucent...)
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cg.translucent = len(m.Translucent) > 0
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gl.BindBuffer(gl.ARRAY_BUFFER, cg.vbo)
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gl.BufferData(gl.ARRAY_BUFFER, len(all)*int(unsafe.Sizeof(mesh.Vertex{})), gl.Ptr(all), gl.STATIC_DRAW)
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// 索引：每面 4 顶点四边形 → 2 三角形（0-1-2-2-3-0）
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idx := make([]uint32, 0, len(all)/4*6)
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for base := 0; base+3 < len(all); base += 4 {
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b := uint32(base)
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idx = append(idx, b, b+1, b+2, b+2, b+3, b)
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}
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gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, cg.ibo)
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gl.BufferData(gl.ELEMENT_ARRAY_BUFFER, len(idx)*4, gl.Ptr(idx), gl.STATIC_DRAW)
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// 顶点属性布局（渲染.md §5 顶点格式）
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stride := int32(unsafe.Sizeof(mesh.Vertex{}))
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gl.EnableVertexAttribArray(0)
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gl.VertexAttribPointer(0, 3, gl.FLOAT, false, stride, gl.PtrOffset(0))
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gl.EnableVertexAttribArray(1)
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gl.VertexAttribPointer(1, 2, gl.FLOAT, false, stride, gl.PtrOffset(3*4))
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gl.EnableVertexAttribArray(2)
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gl.VertexAttribPointer(2, 2, gl.UNSIGNED_BYTE, false, stride, gl.PtrOffset(5*4))
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gl.BindVertexArray(0)
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cg.idxCount = int32(len(m.Opaque) / 4 * 6)
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cg.idxCut = int32(len(m.Cutout) / 4 * 6)
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cg.idxTrans = int32(len(m.Translucent) / 4 * 6)
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r.chunks[k] = cg
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}
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// RemoveChunk 移除区块网格（区块卸载时调用）。
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func (r *Renderer) RemoveChunk(cx, cz int32) {
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k := chunkKey(cx, cz)
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if cg, ok := r.chunks[k]; ok {
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cg.destroy()
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delete(r.chunks, k)
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}
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}
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// destroy 释放 GPU 资源。
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func (cg *chunkGL) destroy() {
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if cg.vao != 0 {
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gl.DeleteVertexArrays(1, &cg.vao)
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}
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if cg.vbo != 0 {
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gl.DeleteBuffers(1, &cg.vbo)
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}
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if cg.ibo != 0 {
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gl.DeleteBuffers(1, &cg.ibo)
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}
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cg.vao, cg.vbo, cg.ibo = 0, 0, 0
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}
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// DrawChunks 绘制全部区块网格（三 pass，渲染.md §6）。
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// chunks：本帧要绘制的区块（已由视锥剔除过滤）。
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func (r *Renderer) DrawChunks(get func(i int) (int32, int32), n int) {
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gl.UseProgram(r.prog)
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gl.ActiveTexture(gl.TEXTURE0)
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gl.BindTexture(gl.TEXTURE_2D, r.atlas)
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var vp [16]float32
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multiply4(&vp, &r.proj, &r.view)
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vpLoc := gl.GetUniformLocation(r.prog, gl.Str("uViewProj\x00"))
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cutLoc := gl.GetUniformLocation(r.prog, gl.Str("uCutout\x00"))
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gl.UniformMatrix4fv(vpLoc, 1, false, &vp[0])
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// pass 1+2：不透明与 cutout（alpha test，不排序）
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gl.Uniform1f(cutLoc, 0)
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drawPass(r, get, n, false, false)
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gl.Uniform1f(cutLoc, 1)
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drawPass(r, get, n, false, true)
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// pass 3：半透明（关闭深度写入，远→近排序由调用方保证顺序）
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gl.Uniform1f(cutLoc, 0)
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gl.DepthMask(false)
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drawPass(r, get, n, true, false)
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gl.DepthMask(true)
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gl.BindVertexArray(0)
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}
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// drawPass 按通道绘制。
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func drawPass(r *Renderer, get func(i int) (int32, int32), n int, translucent, cutout bool) {
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for i := 0; i < n; i++ {
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x, z := get(i)
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cg, ok := r.chunks[chunkKey(x, z)]
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if !ok {
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continue
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}
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base := int32(0)
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count := cg.idxCount
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if cutout {
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base = cg.idxCount
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count = cg.idxCut
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}
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if translucent {
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base = cg.idxCount + cg.idxCut
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count = cg.idxTrans
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}
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if count == 0 {
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continue
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}
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gl.BindVertexArray(cg.vao)
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gl.DrawElements(gl.TRIANGLES, count, gl.UNSIGNED_INT, gl.PtrOffset(int(base)*4))
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}
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}
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// multiply4 列主序 4×4 矩阵乘法：out = a × b。
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func multiply4(out, a, b *[16]float32) {
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for col := 0; col < 4; col++ {
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for row := 0; row < 4; row++ {
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var v float32
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for k := 0; k < 4; k++ {
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v += a[k*4+row] * b[col*4+k]
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}
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out[col*4+row] = v
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}
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}
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}
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