68 lines
1.5 KiB
Go
68 lines
1.5 KiB
Go
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package mat4
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import (
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"zworld/plugin/math"
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"zworld/plugin/math/vec3"
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)
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// Orthographic generates a left-handed orthographic projection matrix.
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// Outputs depth values in the range [0, 1]
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func Orthographic(left, right, bottom, top, near, far float32) T {
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rml, tmb, fmn := (right - left), (top - bottom), (far - near)
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return T{
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2 / rml, 0, 0, 0,
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0, 2 / tmb, 0, 0,
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0, 0, 1 / fmn, 0,
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(right + left) / rml,
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-(top + bottom) / tmb,
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-near / fmn,
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1,
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}
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}
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// OrthographicRZ generates a left-handed orthographic projection matrix.
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// Outputs depth values in the range [1, 0] (reverse Z)
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func OrthographicRZ(left, right, bottom, top, near, far float32) T {
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rml, tmb, fmn := (right - left), (top - bottom), (near - far)
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return T{
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2 / rml, 0, 0, 0,
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0, 2 / tmb, 0, 0,
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0, 0, 1 / fmn, 0,
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-(right + left) / rml,
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-(top + bottom) / tmb,
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near / fmn,
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1,
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}
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}
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// Perspective generates a left-handed perspective projection matrix with reversed depth.
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// Outputs depth values in the range [0, 1]
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func Perspective(fovy, aspect, near, far float32) T {
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fovy = math.DegToRad(fovy)
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tanHalfFov := math.Tan(fovy) / 2
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return T{
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1 / (aspect * tanHalfFov), 0, 0, 0,
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0, -1 / tanHalfFov, 0, 0,
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0, 0, far / (far - near), 1,
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0, 0, -(far * near) / (far - near), 0,
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}
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}
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func LookAt(eye, center, up vec3.T) T {
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f := center.Sub(eye).Normalized()
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r := vec3.Cross(up, f).Normalized()
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u := vec3.Cross(f, r)
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M := T{
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r.X, u.X, f.X, 0,
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r.Y, u.Y, f.Y, 0,
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r.Z, u.Z, f.Z, 0,
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0, 0, 0, 1,
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}
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et := Translate(eye.Scaled(-1))
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return M.Mul(&et)
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}
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