ngzz-mc/internal/render/animals_gl.go

//go:build gl

// 动物方块模型渲染（渲染.md §5.3）：盒模型 + 原版像素 UV，朝向 Entity.Yaw。
package render

import (
	"math"
	"unsafe"

	"mc/internal/mesh"

	"github.com/go-gl/gl/v3.3-core/gl"
)

// DrawAnimalModel 在 (x,y,z)（脚底）以 yaw 绘制盒模型（脸在 −Z；Entity.Yaw 已 +π）。
// tile 为实体图集内动物纹理的归一化矩形；部件 UV 相对 tile 定义。
// flash=true 受击白闪（uTint 提亮）。
func (r *Renderer) DrawAnimalModel(x, y, z, yaw float32, model AnimalModel, tile [4]float32, flash bool) {
	if r.entityTex == 0 || len(model.Parts) == 0 {
		return
	}
	cosY := float32(math.Cos(float64(yaw)))
	sinY := float32(math.Sin(float64(yaw)))
	tw, th := tile[2]-tile[0], tile[3]-tile[1]

	verts := make([]mesh.Vertex, 0, len(model.Parts)*24)
	for _, p := range model.Parts {
		for fi := 0; fi < 6; fi++ {
			uv := p.UV[fi]
			u0 := tile[0] + uv[0]*tw
			v0 := tile[1] + uv[1]*th
			u1 := tile[0] + uv[2]*tw
			v1 := tile[1] + uv[3]*th
			for _, c := range cubeFaces[fi] {
				lx := (c[0]-0.5)*p.W + p.CX
				ly := (c[1]-0.5)*p.H + p.CY
				lz := (c[2]-0.5)*p.D + p.CZ
				// yaw 绕 Y 旋转：模型 +z → (sinY, cosY)
				wx := lx*cosY + lz*sinY
				wz := -lx*sinY + lz*cosY
				var cu, cv float32
				switch fi {
				case 0, 1: // 顶/底：x→u，z→v
					cu, cv = c[0], c[2]
				case 2, 3: // 东/西：z→u，y→v
					cu, cv = c[2], 1-c[1]
				default: // 南/北：x→u，y→v
					cu, cv = c[0], 1-c[1]
				}
				verts = append(verts, mesh.Vertex{
					X: x + wx, Y: y + ly, Z: z + wz,
					U: u0 + (u1-u0)*cu, V: v0 + (v1-v0)*cv,
					Sky: 15, Block: 15,
				})
			}
		}
	}

	if r.animalVao == 0 {
		gl.GenVertexArrays(1, &r.animalVao)
		gl.GenBuffers(1, &r.animalVbo)
		gl.GenBuffers(1, &r.animalIbo)
		gl.BindVertexArray(r.animalVao)
		gl.BindBuffer(gl.ARRAY_BUFFER, r.animalVbo)
		stride := int32(unsafe.Sizeof(mesh.Vertex{}))
		gl.EnableVertexAttribArray(0)
		gl.VertexAttribPointer(0, 3, gl.FLOAT, false, stride, gl.PtrOffset(0))
		gl.EnableVertexAttribArray(1)
		gl.VertexAttribPointer(1, 2, gl.FLOAT, false, stride, gl.PtrOffset(3*4))
		gl.EnableVertexAttribArray(2)
		gl.VertexAttribPointer(2, 2, gl.UNSIGNED_BYTE, false, stride, gl.PtrOffset(5*4))
		// 索引缓冲绑定必须捕获进 VAO（ELEMENT_ARRAY_BUFFER 属 VAO 状态）
		gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, r.animalIbo)
		gl.BindVertexArray(0)
	}

	idx := make([]uint32, 0, len(verts)/4*6)
	for base := 0; base+3 < len(verts); base += 4 {
		b := uint32(base)
		idx = append(idx, b, b+1, b+2, b+2, b+3, b)
	}
	// 数据上传须保持 VAO 绑定（避免污染其他 VAO 的 EBO 状态）
	gl.BindVertexArray(r.animalVao)
	gl.BindBuffer(gl.ARRAY_BUFFER, r.animalVbo)
	gl.BufferData(gl.ARRAY_BUFFER, len(verts)*int(unsafe.Sizeof(mesh.Vertex{})), gl.Ptr(verts), gl.DYNAMIC_DRAW)
	gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, r.animalIbo)
	gl.BufferData(gl.ELEMENT_ARRAY_BUFFER, len(idx)*4, gl.Ptr(idx), gl.DYNAMIC_DRAW)

	gl.UseProgram(r.prog)
	gl.ActiveTexture(gl.TEXTURE0)
	gl.BindTexture(gl.TEXTURE_2D, r.entityTex)
	var vp [16]float32
	multiply4(&vp, &r.proj, &r.view)
	gl.UniformMatrix4fv(gl.GetUniformLocation(r.prog, gl.Str("uViewProj\x00")), 1, false, &vp[0])
	gl.Uniform3f(gl.GetUniformLocation(r.prog, gl.Str("uOffset\x00")), 0, 0, 0) // 顶点已烘焙为世界坐标
	gl.Uniform1f(gl.GetUniformLocation(r.prog, gl.Str("uCutout\x00")), 1)       // alpha test：剔除纹理透明区域
	if flash {
		gl.Uniform4f(gl.GetUniformLocation(r.prog, gl.Str("uTint\x00")), 2.5, 2.5, 2.5, 1)
	} else {
		gl.Uniform4f(gl.GetUniformLocation(r.prog, gl.Str("uTint\x00")), 1, 1, 1, 1)
	}
	gl.Uniform2f(gl.GetUniformLocation(r.prog, gl.Str("uBill\x00")), 1, 0) // 非广告牌路径
	gl.Uniform2f(gl.GetUniformLocation(r.prog, gl.Str("uUVMin\x00")), 0, 0)
	gl.Uniform2f(gl.GetUniformLocation(r.prog, gl.Str("uUVMax\x00")), 1, 1)

	gl.BindVertexArray(r.animalVao)
	gl.DrawElements(gl.TRIANGLES, int32(len(idx)), gl.UNSIGNED_INT, gl.PtrOffset(0))
	gl.BindVertexArray(0)
}