Bugfix #26128

Compositor/texture nodes: math node now allows to use pow() for
negative raising too, but only when that value is near-integer.
For other negative cases result is zero.
Patch provided by Aurel W

source/blender/nodes/intern/CMP_nodes/CMP_math.c

@@ -94,11 +94,18 @@ static void do_math(bNode *node, float *out, float *in, float *in2)
 		break;
 	case 10: /* Power */
 		{
-			/* Don't want any imaginary numbers... */
-			if( in[0] >= 0 )
+			/* Only raise negative numbers by full integers */
+			if( in[0] >= 0 ) {
 				out[0]= pow(in[0], in2[0]);
-			else
-				out[0]= 0.0;
+            } else {
+                float y_mod_1 = fmod(in2[0], 1);
+				/* if input value is not nearly an integer, fall back to zero, nicer than straight rounding */
+                if (y_mod_1 > 0.999 || y_mod_1 < 0.001) {
+                    out[0]= pow(in[0], round(in2[0]));
+                } else {
+                    out[0] = 0.0;
+                }
+            }
 		}
 		break;
 	case 11: /* Logarithm */