Added terrain and basic terrain textures

Assets/Filamented/FilamentCommonMath.cginc

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+#ifndef FILAMENT_COMMON_MATH
+#define FILAMENT_COMMON_MATH
+//------------------------------------------------------------------------------
+// Common math
+//------------------------------------------------------------------------------
+
+/** @public-api */
+#define PI                 3.14159265359
+/** @public-api */
+#define HALF_PI            1.570796327
+
+#define MEDIUMP_FLT_MAX    65504.0
+#define MEDIUMP_FLT_MIN    0.00006103515625
+
+#ifdef TARGET_MOBILE
+#define FLT_EPS            MEDIUMP_FLT_MIN
+#define saturateMediump(x) min(x, MEDIUMP_FLT_MAX)
+#else
+#define FLT_EPS            1e-5
+#define saturateMediump(x) x
+#endif
+
+#ifdef TARGET_MOBILE
+#define PREVENT_DIV0(n, d, magic)   ((n) / max(d, magic))
+#else
+#define PREVENT_DIV0(n, d, magic)   ((n) / (d))
+#endif
+
+#define atan(x,y)          atan2(y,x)
+
+//------------------------------------------------------------------------------
+// Scalar operations
+//------------------------------------------------------------------------------
+
+/**
+ * Computes x^5 using only multiply operations.
+ *
+ * @public-api
+ */
+half pow5(half x) {
+    half x2 = x * x;
+    return x2 * x2 * x;
+}
+
+/**
+ * Computes x^2 as a single multiplication.
+ *
+ * @public-api
+ */
+half sq(half x) {
+    return x * x;
+}
+
+//------------------------------------------------------------------------------
+// Vector operations
+//------------------------------------------------------------------------------
+
+/**
+ * Returns the maximum component of the specified vector.
+ *
+ * @public-api
+ */
+half max3(const half3 v) {
+    return max(v.x, max(v.y, v.z));
+}
+
+half vmax(const half2 v) {
+    return max(v.x, v.y);
+}
+
+half vmax(const half3 v) {
+    return max(v.x, max(v.y, v.z));
+}
+
+half vmax(const half4 v) {
+    return max(max(v.x, v.y), max(v.y, v.z));
+}
+
+/**
+ * Returns the minimum component of the specified vector.
+ *
+ * @public-api
+ */
+half min3(const half3 v) {
+    return min(v.x, min(v.y, v.z));
+}
+
+half vmin(const half2 v) {
+    return min(v.x, v.y);
+}
+
+half vmin(const half3 v) {
+    return min(v.x, min(v.y, v.z));
+}
+
+half vmin(const half4 v) {
+    return min(min(v.x, v.y), min(v.y, v.z));
+}
+
+//------------------------------------------------------------------------------
+// Trigonometry
+//------------------------------------------------------------------------------
+
+/**
+ * Approximates acos(x) with a max absolute error of 9.0x10^-3.
+ * Valid in the range -1..1.
+ */
+half acosFast(half x) {
+    // Lagarde 2014, "Inverse trigonometric functions GPU optimization for AMD GCN architecture"
+    // This is the approximation of degree 1, with a max absolute error of 9.0x10^-3
+    half y = abs(x);
+    half p = -0.1565827 * y + 1.570796;
+    p *= sqrt(1.0 - y);
+    return x >= 0.0 ? p : PI - p;
+}
+
+/**
+ * Approximates acos(x) with a max absolute error of 9.0x10^-3.
+ * Valid only in the range 0..1.
+ */
+half acosFastPositive(half x) {
+    half p = -0.1565827 * x + 1.570796;
+    return p * sqrt(1.0 - x);
+}
+#endif // FILAMENT_COMMON_MATH