PNG writer

shaders/fisheye-equirectangular-mirror/shader.json

@@ -0,0 +1,90 @@
+{
+  "id": "fisheye-equirectangular-mirror",
+  "name": "Fisheye Equirectangular Mirror",
+  "description": "Unwraps a single fisheye lens into a 360x180 equirectangular map by mirroring the rear hemisphere into the same fisheye source.",
+  "category": "Projection",
+  "entryPoint": "shadeVideo",
+  "parameters": [
+    {
+      "id": "lensFovDegrees",
+      "label": "Lens FOV",
+      "type": "float",
+      "default": 180.0,
+      "min": 1.0,
+      "max": 220.0,
+      "step": 0.1
+    },
+    {
+      "id": "center",
+      "label": "Optical Center",
+      "type": "vec2",
+      "default": [0.5, 0.5],
+      "min": [0.0, 0.0],
+      "max": [1.0, 1.0],
+      "step": [0.001, 0.001]
+    },
+    {
+      "id": "radius",
+      "label": "Fisheye Radius",
+      "type": "vec2",
+      "default": [0.5, 0.5],
+      "min": [0.001, 0.001],
+      "max": [2.0, 2.0],
+      "step": [0.001, 0.001]
+    },
+    {
+      "id": "yawDegrees",
+      "label": "Yaw",
+      "type": "float",
+      "default": 0.0,
+      "min": -180.0,
+      "max": 180.0,
+      "step": 0.1
+    },
+    {
+      "id": "pitchDegrees",
+      "label": "Pitch",
+      "type": "float",
+      "default": 0.0,
+      "min": -120.0,
+      "max": 120.0,
+      "step": 0.1
+    },
+    {
+      "id": "rollDegrees",
+      "label": "Roll",
+      "type": "float",
+      "default": 0.0,
+      "min": -180.0,
+      "max": 180.0,
+      "step": 0.1
+    },
+    {
+      "id": "seamAngleDegrees",
+      "label": "Seam Angle",
+      "type": "float",
+      "default": 0.0,
+      "min": -180.0,
+      "max": 180.0,
+      "step": 0.1
+    },
+    {
+      "id": "fisheyeModel",
+      "label": "Fisheye Model",
+      "type": "enum",
+      "default": "equidistant",
+      "options": [
+        { "value": "equidistant", "label": "Equidistant" },
+        { "value": "equisolid", "label": "Equisolid" },
+        { "value": "stereographic", "label": "Stereographic" },
+        { "value": "orthographic", "label": "Orthographic" }
+      ]
+    },
+    {
+      "id": "outsideColor",
+      "label": "Outside Color",
+      "type": "color",
+      "default": [0.0, 0.0, 0.0, 1.0]
+    }
+  ]
+}

shaders/fisheye-equirectangular-mirror/shader.slang

@@ -0,0 +1,93 @@
+static const float PI = 3.14159265358979323846;
+static const float TWO_PI = 6.28318530717958647692;
+
+float radiansFromDegrees(float degrees)
+{
+	return degrees * (PI / 180.0);
+}
+
+float3 rotateX(float3 ray, float angle)
+{
+	float s = sin(angle);
+	float c = cos(angle);
+	return float3(ray.x, c * ray.y - s * ray.z, s * ray.y + c * ray.z);
+}
+
+float3 rotateY(float3 ray, float angle)
+{
+	float s = sin(angle);
+	float c = cos(angle);
+	return float3(c * ray.x + s * ray.z, ray.y, -s * ray.x + c * ray.z);
+}
+
+float3 rotateZ(float3 ray, float angle)
+{
+	float s = sin(angle);
+	float c = cos(angle);
+	return float3(c * ray.x - s * ray.y, s * ray.x + c * ray.y, ray.z);
+}
+
+float normalizedFisheyeRadius(float theta, float halfFov)
+{
+	float safeHalfFov = max(halfFov, 0.0001);
+
+	if (fisheyeModel == 1)
+	{
+		return sin(theta * 0.5) / max(sin(safeHalfFov * 0.5), 0.0001);
+	}
+	else if (fisheyeModel == 2)
+	{
+		return tan(theta * 0.5) / max(tan(safeHalfFov * 0.5), 0.0001);
+	}
+	else if (fisheyeModel == 3)
+	{
+		return sin(theta) / max(sin(safeHalfFov), 0.0001);
+	}
+
+	return theta / safeHalfFov;
+}
+
+float3 equirectangularRay(float2 uv)
+{
+	float longitude = (uv.x - 0.5) * TWO_PI + radiansFromDegrees(seamAngleDegrees);
+	float latitude = (0.5 - uv.y) * PI;
+	float latitudeCos = cos(latitude);
+
+	return normalize(float3(
+		sin(longitude) * latitudeCos,
+		sin(latitude),
+		cos(longitude) * latitudeCos
+	));
+}
+
+float4 shadeVideo(ShaderContext context)
+{
+	float3 ray = equirectangularRay(context.uv);
+
+	ray = rotateZ(ray, radiansFromDegrees(rollDegrees));
+	ray = rotateX(ray, radiansFromDegrees(-pitchDegrees));
+	ray = rotateY(ray, radiansFromDegrees(yawDegrees));
+
+	// Mirror the rear hemisphere into the front-facing fisheye image so one
+	// circular lens source fills both halves of the equirectangular output.
+	ray.z = abs(ray.z);
+	ray = normalize(ray);
+
+	float halfFov = radiansFromDegrees(clamp(lensFovDegrees, 1.0, 220.0) * 0.5);
+	float theta = acos(clamp(ray.z, -1.0, 1.0));
+	if (theta > halfFov)
+		return outsideColor;
+
+	float phi = atan2(ray.y, ray.x);
+	float fisheyeRadius = normalizedFisheyeRadius(theta, halfFov);
+
+	float2 sourceUv = float2(
+		center.x + cos(phi) * fisheyeRadius * radius.x,
+		center.y - sin(phi) * fisheyeRadius * radius.y
+	);
+
+	if (sourceUv.x < 0.0 || sourceUv.x > 1.0 || sourceUv.y < 0.0 || sourceUv.y > 1.0)
+		return outsideColor;
+
+	return sampleVideo(sourceUv);
+}