completed fog example (#18)

* complete fog example
as both fog and basic lighting need the light system it made sense
to seperate it out, there are a few functions from raymath
int rlmath.py

* added shaders custom uniform

* added shaders_texture_waves.py

* added shaders_texture_drawing.py

* bug fix - unwanted transparent effect!

Co-authored-by: codifies <nospam@antispam.com>

examples/shaders/rlmath.py

@@ -0,0 +1,93 @@
+# just a few functions from raymath
+from raylib.dynamic import raylib as rl, ffi
+import math
+
+PI = 3.14159265358979323846
+DEG2RAD = (PI/180.0)
+RAD2DEG = (180.0/PI)
+
+def Clamp(value: float, minv: float, maxv: float):
+    #res = value < minv ? minv : value
+    res = minv if value < minv else value
+    #return res > maxv ? maxv : res
+    return maxv if res > maxv else res
+
+def Lerp(start: float, end: float, amount: float):
+    return start + amount*(end - start)
+
+
+def Vector2Zero():
+    return ffi.new("struct Vector2 *",[ 0, 0])
+
+def Vector3Zero():
+    return ffi.new("struct Vector3 *",[ 0, 0, 0])
+    
+def MatrixRotateX(angle):
+    result = MatrixIdentity();
+
+    cosres = math.cos(angle);
+    sinres = math.sin(angle);
+
+    result.m5 = cosres;
+    result.m6 = -sinres;
+    result.m9 = sinres;
+    result.m10 = cosres;
+
+    return result;
+
+
+
+def MatrixRotateY(angle):
+    result = MatrixIdentity()
+
+    cosres = math.cos(angle);
+    sinres = math.sin(angle);
+
+    result.m0 = cosres;
+    result.m2 = sinres;
+    result.m8 = -sinres;
+    result.m10 = cosres;
+
+    return result;
+
+
+def MatrixIdentity():
+    result = ffi.new("struct Matrix *",[ 1.0, 0.0, 0.0, 0.0,0.0, 1.0, 0.0, 0.0,    0.0, 0.0, 1.0, 0.0,   0.0, 0.0, 0.0, 1.0 ])
+    return result
+
+
+
+def MatrixRotateZ(angle):
+    result = MatrixIdentity();
+
+    cosres = math.cos(angle);
+    sinres = math.sin(angle);
+
+    result.m0 = cosres;
+    result.m1 = -sinres;
+    result.m4 = sinres;
+    result.m5 = cosres;
+
+    return result
+
+
+def MatrixMultiply(left,  right):
+    result = ffi.new("struct Matrix *")
+    result.m0 = left.m0*right.m0 + left.m1*right.m4 + left.m2*right.m8 + left.m3*right.m12;
+    result.m1 = left.m0*right.m1 + left.m1*right.m5 + left.m2*right.m9 + left.m3*right.m13;
+    result.m2 = left.m0*right.m2 + left.m1*right.m6 + left.m2*right.m10 + left.m3*right.m14;
+    result.m3 = left.m0*right.m3 + left.m1*right.m7 + left.m2*right.m11 + left.m3*right.m15;
+    result.m4 = left.m4*right.m0 + left.m5*right.m4 + left.m6*right.m8 + left.m7*right.m12;
+    result.m5 = left.m4*right.m1 + left.m5*right.m5 + left.m6*right.m9 + left.m7*right.m13;
+    result.m6 = left.m4*right.m2 + left.m5*right.m6 + left.m6*right.m10 + left.m7*right.m14;
+    result.m7 = left.m4*right.m3 + left.m5*right.m7 + left.m6*right.m11 + left.m7*right.m15;
+    result.m8 = left.m8*right.m0 + left.m9*right.m4 + left.m10*right.m8 + left.m11*right.m12;
+    result.m9 = left.m8*right.m1 + left.m9*right.m5 + left.m10*right.m9 + left.m11*right.m13;
+    result.m10 = left.m8*right.m2 + left.m9*right.m6 + left.m10*right.m10 + left.m11*right.m14;
+    result.m11 = left.m8*right.m3 + left.m9*right.m7 + left.m10*right.m11 + left.m11*right.m15;
+    result.m12 = left.m12*right.m0 + left.m13*right.m4 + left.m14*right.m8 + left.m15*right.m12;
+    result.m13 = left.m12*right.m1 + left.m13*right.m5 + left.m14*right.m9 + left.m15*right.m13;
+    result.m14 = left.m12*right.m2 + left.m13*right.m6 + left.m14*right.m10 + left.m15*right.m14;
+    result.m15 = left.m12*right.m3 + left.m13*right.m7 + left.m14*right.m11 + left.m15*right.m15;
+
+    return result