add mat4.rotate to maths_inline.lua

res/modules/internal/maths_inline.lua

@@ -1,3 +1,8 @@
+local sin = math.sin
+local cos = math.cos
+local sqrt = math.sqrt
+local rad = math.rad
+
 -- =================================================== --
 -- ====================== vec3 ======================= --
 -- =================================================== --
@@ -252,3 +257,75 @@ function mat4.idt(dst)
         0, 0, 0, 1
     }
 end
+
+function mat4.rotate(...)
+    local argc = select("#", ...)
+
+    local matrix, axis, angle, dst
+
+    if argc == 2 then
+        axis, angle = ...
+        matrix = mat4.idt()
+    elseif argc == 3 then
+        matrix, axis, angle = ...
+    elseif argc == 4 then
+        matrix, axis, angle, dst = ...
+    else
+        error("invalid arguments number (2, 3 or 4 expected)")
+    end
+
+    angle = rad(angle)
+
+    local x = axis[1]
+    local y = axis[2]
+    local z = axis[3]
+
+    local len = sqrt(x*x + y*y + z*z)
+    if len == 0 then
+        error("rotation axis has zero length")
+    end
+
+    x = x / len
+    y = y / len
+    z = z / len
+
+    local c = cos(angle)
+    local s = sin(angle)
+    local t = 1 - c
+
+    local r00 = t*x*x + c
+    local r01 = t*x*y - s*z
+    local r02 = t*x*z + s*y
+
+    local r10 = t*x*y + s*z
+    local r11 = t*y*y + c
+    local r12 = t*y*z - s*x
+
+    local r20 = t*x*z - s*y
+    local r21 = t*y*z + s*x
+    local r22 = t*z*z + c
+
+    local out = dst or {}
+
+    out[1] = matrix[1]*r00 + matrix[5]*r10 + matrix[9]*r20
+    out[2] = matrix[2]*r00 + matrix[6]*r10 + matrix[10]*r20
+    out[3] = matrix[3]*r00 + matrix[7]*r10 + matrix[11]*r20
+    out[4] = matrix[4]*r00 + matrix[8]*r10 + matrix[12]*r20
+
+    out[5] = matrix[1]*r01 + matrix[5]*r11 + matrix[9]*r21
+    out[6] = matrix[2]*r01 + matrix[6]*r11 + matrix[10]*r21
+    out[7] = matrix[3]*r01 + matrix[7]*r11 + matrix[11]*r21
+    out[8] = matrix[4]*r01 + matrix[8]*r11 + matrix[12]*r21
+
+    out[9]  = matrix[1]*r02 + matrix[5]*r12 + matrix[9]*r22
+    out[10] = matrix[2]*r02 + matrix[6]*r12 + matrix[10]*r22
+    out[11] = matrix[3]*r02 + matrix[7]*r12 + matrix[11]*r22
+    out[12] = matrix[4]*r02 + matrix[8]*r12 + matrix[12]*r22
+
+    out[13] = matrix[13]
+    out[14] = matrix[14]
+    out[15] = matrix[15]
+    out[16] = matrix[16]
+
+    return out
+end