Integrate metallic eye shader

1 files changed, 104 insertions, 0 deletions

diff --git a/eyes.cginc b/eyes.cginc
new file mode 100644
index 0000000..c5fbc1b
--- /dev/null
+++ b/eyes.cginc
@@ -0,0 +1,104 @@
+#ifndef __EYES_INC
+#define __EYES_INC
+
+#if defined(_GIMMICK_EYES_00)
+
+float eyes00_distance_from_sphere(float3 p, float3 c, float r)
+{
+    return length(p - c) - r;
+}
+
+float eyes00_map(float3 p)
+{
+    float t = _Time.y;
+    float theta = sin(_Time[0]) / 2;
+    float2x2 rot = float2x2(
+      cos(theta), -sin(theta),
+      sin(theta), cos(theta));
+
+    float dist = 1000 * 1000 * 1000;
+    #define Y_STEPS 5
+    for (int y = 0; y < Y_STEPS; y++)
+    {
+      const int yy = y - Y_STEPS/2;
+      #define X_STEPS 5
+      for (int x = 0; x < X_STEPS; x++)
+      {
+        const int xx = x - X_STEPS/2;
+        float2 pp = float2(xx * 2, yy * 2);
+        pp = mul(rot, pp);
+        float radius = cos((x + y + _Time[0]) * 3.14159) * 0.5 + 1;
+        float sphere = eyes00_distance_from_sphere(p, float3(pp.x, pp.y, 0.0), radius);
+        dist = min(dist, sphere);
+        dist += sin(5.0 * pp.x) * sin(5.0 * pp.y) * 0.5;
+      }
+    }
+
+    return dist;
+}
+
+float3 eyes00_calc_normal(in float3 p)
+{
+    const float3 small_step = float3(0.0001, 0.0, 0.0);
+
+    float gradient_x = eyes00_map(p + small_step.xyy) - eyes00_map(p - small_step.xyy);
+    float gradient_y = eyes00_map(p + small_step.yxy) - eyes00_map(p - small_step.yxy);
+    float gradient_z = eyes00_map(p + small_step.yyx) - eyes00_map(p - small_step.yyx);
+
+    float3 normal = float3(gradient_x, gradient_y, gradient_z);
+
+    return normalize(normal);
+}
+
+float3 __eyes00_march(float3 ro, float3 rd, inout float3 normal)
+{
+    float total_distance_traveled = 0.0;
+    const float MINIMUM_HIT_DISTANCE = 0.001;
+    const float MAXIMUM_TRACE_DISTANCE = 1000.0;
+
+    #define EYES00_MARCH_STEPS 10
+    float distance_to_closest;
+    float3 current_position;
+    for (int i = 0; i < EYES00_MARCH_STEPS; i++)
+    {
+        current_position = ro + total_distance_traveled * rd;
+
+        distance_to_closest = eyes00_map(current_position);
+
+        if (distance_to_closest < MINIMUM_HIT_DISTANCE) 
+        {
+          break;
+        }
+
+        if (total_distance_traveled > MAXIMUM_TRACE_DISTANCE)
+        {
+            break;
+        }
+        total_distance_traveled += distance_to_closest;
+    }
+
+    if (distance_to_closest < MINIMUM_HIT_DISTANCE) {
+      normal = eyes00_calc_normal(current_position);
+      return float3(1.0, 1.0, 1.0);
+    }
+
+    return float3(0, 0, 0);
+}
+
+float4 eyes00_march(float2 uv, inout float3 normal)
+{
+    uv = uv * 2.0 - 1.0;
+
+    float3 camera_position = float3(0.0, 0.0, -5.0);
+    float3 ro = camera_position;
+    float3 rd = float3(uv.x, uv.y, 1.0);
+
+    float3 shaded_color = __eyes00_march(ro, rd, normal);
+
+    return float4(shaded_color, 1.0);
+}
+
+#endif  // _EYES
+
+#endif  // __EYES_INC
+