138 lines
4.5 KiB
Go
138 lines
4.5 KiB
Go
// Package mesh 区块网格构建：面剔除 + 顶点格式 + 光照（场景/渲染.md §3）。
|
||
//
|
||
// 网格在 CPU 构建（worker 池），GL 只负责上传——渲染 goroutine 不产生分配压力。
|
||
package mesh
|
||
|
||
import (
|
||
"mc/internal/block"
|
||
"mc/internal/chunk"
|
||
)
|
||
|
||
// Vertex 顶点格式（渲染.md §5）：位置 + UV + 天空/方块光各 4-bit。
|
||
type Vertex struct {
|
||
X, Y, Z float32
|
||
U, V float32
|
||
Sky, Block uint8
|
||
}
|
||
|
||
// ChunkMesh 一个区块的三类网格（渲染.md §6 三 pass）。
|
||
// 每面 4 顶点（四边形），渲染层用索引缓冲扩为 2 三角形（顺序 0-1-2-2-3-0）。
|
||
type ChunkMesh struct {
|
||
Opaque []Vertex // 不透明（主 pass）
|
||
Cutout []Vertex // alpha test（树叶/玻璃）
|
||
Translucent []Vertex // 半透明（水，远→近排序 pass）
|
||
}
|
||
|
||
// Neighbor 邻居方块查询（跨区块面剔除用，区块管理.md §6）。
|
||
type Neighbor func(x, y, z int32) block.State
|
||
|
||
// UVFunc 纹理键 → 图集 UV（归一化坐标，含 inset）。
|
||
type UVFunc func(texKey string) (u0, v0, u1, v1 float32, ok bool)
|
||
|
||
// Builder 网格构建器。
|
||
type Builder struct {
|
||
reg *block.Registry
|
||
uv UVFunc
|
||
}
|
||
|
||
// NewBuilder 创建构建器。
|
||
func NewBuilder(reg *block.Registry, uv UVFunc) *Builder {
|
||
return &Builder{reg: reg, uv: uv}
|
||
}
|
||
|
||
// face 一个面的 4 个角偏移与朝向。
|
||
type faceDef struct {
|
||
dir [3]int32
|
||
corners [4][3]int32
|
||
}
|
||
|
||
// faces 六面定义（角顺序与 UV 顶点顺序一致）。
|
||
var faces = [6]faceDef{
|
||
{dir: [3]int32{0, 1, 0}, corners: [4][3]int32{{0, 1, 0}, {1, 1, 0}, {1, 1, 1}, {0, 1, 1}}}, // 顶
|
||
{dir: [3]int32{0, -1, 0}, corners: [4][3]int32{{0, 0, 1}, {1, 0, 1}, {1, 0, 0}, {0, 0, 0}}}, // 底
|
||
{dir: [3]int32{1, 0, 0}, corners: [4][3]int32{{1, 0, 0}, {1, 0, 1}, {1, 1, 1}, {1, 1, 0}}}, // 东(+x)
|
||
{dir: [3]int32{-1, 0, 0}, corners: [4][3]int32{{0, 0, 1}, {0, 0, 0}, {0, 1, 0}, {0, 1, 1}}}, // 西(-x)
|
||
{dir: [3]int32{0, 0, 1}, corners: [4][3]int32{{1, 0, 1}, {0, 0, 1}, {0, 1, 1}, {1, 1, 1}}}, // 南(+z)
|
||
{dir: [3]int32{0, 0, -1}, corners: [4][3]int32{{0, 0, 0}, {1, 0, 0}, {1, 1, 0}, {0, 1, 0}}}, // 北(-z)
|
||
}
|
||
|
||
// faceTexture 面方向 → 注册表纹理面名（block.Registry.Texture 参数）。
|
||
var faceTexture = [6]string{"up", "down", "east", "west", "south", "north"}
|
||
|
||
// Build 构建区块网格（面剔除：仅当邻格非完全不透明时生成该面，渲染.md §3.1）。
|
||
func (b *Builder) Build(c *chunk.Chunk, nb Neighbor) *ChunkMesh {
|
||
m := &ChunkMesh{}
|
||
blocks := c.Snapshot()
|
||
baseX, baseZ := float32(c.CX*16), float32(c.CZ*16)
|
||
|
||
for x := 0; x < 16; x++ {
|
||
for y := 0; y < chunk.Height; y++ {
|
||
for z := 0; z < 16; z++ {
|
||
s := blocks[chunk.Index(x, y, z)]
|
||
if s == block.Air {
|
||
continue
|
||
}
|
||
var target *[]Vertex
|
||
switch {
|
||
case b.reg.IsTranslucent(s):
|
||
target = &m.Translucent
|
||
case b.reg.IsCutout(s):
|
||
target = &m.Cutout
|
||
default:
|
||
target = &m.Opaque
|
||
}
|
||
wx := int32(x) + c.CX*16
|
||
wy := int32(y)
|
||
wz := int32(z) + c.CZ*16
|
||
sky, blk := c.SkyLight(x, y, z), c.BlockLight(x, y, z)
|
||
|
||
for fi, f := range faces {
|
||
nx := wx + f.dir[0]
|
||
ny := wy + f.dir[1]
|
||
nz := wz + f.dir[2]
|
||
neighbor := nb(nx, ny, nz)
|
||
if b.reg.IsOpaque(neighbor) {
|
||
continue // 面被不透明邻格遮挡（面剔除）
|
||
}
|
||
// 同类型邻格也剔除（水贴水不渲染内面；树叶相邻保留边缘，简化规则）
|
||
if neighbor != block.Air && !b.reg.IsOpaque(neighbor) &&
|
||
b.reg.IsTranslucent(neighbor) == b.reg.IsTranslucent(s) && b.reg.IsTranslucent(s) {
|
||
continue
|
||
}
|
||
texKey := b.reg.Texture(s, faceTexture[fi])
|
||
u0, v0, u1, v1, ok := b.uv(texKey)
|
||
if !ok {
|
||
u0, v0, u1, v1 = 0, 0, 1, 1
|
||
}
|
||
for _, corner := range f.corners {
|
||
*target = append(*target, Vertex{
|
||
X: baseX + float32(x) + float32(corner[0]),
|
||
Y: float32(y) + float32(corner[1]),
|
||
Z: baseZ + float32(z) + float32(corner[2]),
|
||
U: u0 + (u1-u0)*float32(cornerUV(corner, f)[0]),
|
||
V: v0 + (v1-v0)*float32(cornerUV(corner, f)[1]),
|
||
Sky: sky,
|
||
Block: blk,
|
||
})
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
return m
|
||
}
|
||
|
||
// cornerUV 角在面上的 UV 权重（0/1），顺序与 corners 一致。
|
||
func cornerUV(c [3]int32, f faceDef) [2]int32 {
|
||
var u, v int32
|
||
switch f.dir {
|
||
case [3]int32{0, 1, 0}, [3]int32{0, -1, 0}: // 顶/底：x→u，z→v
|
||
u, v = c[0], c[2]
|
||
case [3]int32{1, 0, 0}, [3]int32{-1, 0, 0}: // 东/西：z→u，y→v
|
||
u, v = c[2], 1-c[1]
|
||
default: // 南/北：x→u，y→v
|
||
u, v = c[0], 1-c[1]
|
||
}
|
||
return [2]int32{u, v}
|
||
}
|