73 lines
2.1 KiB
Go
73 lines
2.1 KiB
Go
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// Package camera 第一人称相机：欧拉角（yaw/pitch）与视图/投影矩阵（渲染.md 配套）。
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//
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// 约定：yaw=0 朝向 -Z（GL 习惯），pitch>0 抬头；视图矩阵为列主序（GL 风格）。
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package camera
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import "math"
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// Camera 第一人称相机。
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type Camera struct {
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Pos [3]float64 // 眼睛位置
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Yaw float64 // 水平角（弧度）
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Pitch float64 // 俯仰角（弧度）
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FOV float64 // 垂直视场角（度）
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}
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// New 创建相机。
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func New(pos [3]float64, yaw, pitch, fov float64) *Camera {
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return &Camera{Pos: pos, Yaw: yaw, Pitch: pitch, FOV: fov}
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}
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// Forward 前方向（单位向量）。
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func (c *Camera) Forward() [3]float64 {
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cp, sp := math.Cos(c.Pitch), math.Sin(c.Pitch)
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cy, sy := math.Cos(c.Yaw), math.Sin(c.Yaw)
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return [3]float64{-sy * cp, sp, -cy * cp}
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}
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// Right 右方向（单位向量，水平）。
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func (c *Camera) Right() [3]float64 {
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cy, sy := math.Cos(c.Yaw), math.Sin(c.Yaw)
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return [3]float64{cy, 0, -sy}
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}
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// View 视图矩阵（列主序 4×4，GL 用）。
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func (c *Camera) View() [16]float32 {
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// 旋转 = RotX(-pitch) × RotY(-yaw)，再平移 -pos
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cp, sp := math.Cos(-c.Pitch), math.Sin(-c.Pitch)
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cy, sy := math.Cos(-c.Yaw), math.Sin(-c.Yaw)
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// R = RotY(-yaw) × RotX(-pitch) 的计算结果（行主序推导后转列主序）
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// 列主序布局: m[col*4+row]
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m := [16]float32{}
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m[0] = float32(cy)
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m[1] = float32(-sy * sp)
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m[2] = float32(-sy * cp)
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m[4] = float32(sy)
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m[5] = float32(cy * sp)
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m[6] = float32(cy * cp)
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m[8] = 0
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m[9] = float32(cp)
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m[10] = float32(-sp)
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m[15] = 1
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// 平移部分：t = -R·pos
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px, py, pz := float32(c.Pos[0]), float32(c.Pos[1]), float32(c.Pos[2])
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m[12] = -(m[0]*px + m[4]*py + m[8]*pz)
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m[13] = -(m[1]*px + m[5]*py + m[9]*pz)
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m[14] = -(m[2]*px + m[6]*py + m[10]*pz)
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return m
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}
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// Projection 透视投影矩阵（列主序，GL 用）。
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func (c *Camera) Projection(aspect, near, far float64) [16]float32 {
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f := 1.0 / math.Tan(c.FOV*math.Pi/360.0)
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var m [16]float32
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m[0] = float32(f / aspect)
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m[5] = float32(f)
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m[10] = float32((far + near) / (near - far))
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m[11] = -1
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m[14] = float32(2 * far * near / (near - far))
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return m
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}
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