/************************************************************************************
Copyright : Copyright (c) Facebook Technologies, LLC and its affiliates. All rights reserved.

Your use of this SDK or tool is subject to the Oculus SDK License Agreement, available at
https://developer.oculus.com/licenses/oculussdk/

Unless required by applicable law or agreed to in writing, the Utilities SDK distributed
under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
ANY KIND, either express or implied. See the License for the specific language governing
permissions and limitations under the License.
************************************************************************************/

Shader "Interaction/DotGridUnlit"
{
    Properties {
        _Color("Color", Color) = (0, 0, 0, 1)

        // rows, columns, radius
        _Dimensions("Dimensions", Vector) = (1, 1, .1, 0)
    }

    SubShader
    {
        Tags {"Queue"="Transparent" "RenderType"="Transparent"}
        ZWrite Off
        Blend SrcAlpha OneMinusSrcAlpha
        LOD 100

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma multi_compile_instancing

            #include "UnityCG.cginc"

            struct appdata
            {
                UNITY_VERTEX_INPUT_INSTANCE_ID
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct v2f
            {
                UNITY_VERTEX_INPUT_INSTANCE_ID
                float4 vertex : SV_POSITION;
                float2 uv : TEXCOORD0;
            };

            UNITY_INSTANCING_BUFFER_START(Props)
                UNITY_DEFINE_INSTANCED_PROP(fixed4, _Color)
                UNITY_DEFINE_INSTANCED_PROP(fixed4, _Dimensions)
            UNITY_INSTANCING_BUFFER_END(Props)

            v2f vert (appdata v)
            {
                v2f o;
                UNITY_SETUP_INSTANCE_ID(v);
                UNITY_TRANSFER_INSTANCE_ID(v, o);

                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;

                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                UNITY_SETUP_INSTANCE_ID(i);

                float4 color = UNITY_ACCESS_INSTANCED_PROP(Props, _Color);
                float4 dimensions = UNITY_ACCESS_INSTANCED_PROP(Props, _Dimensions);

                float2 diameter = float2(1.0f/dimensions.x, 1.0f/dimensions.y);
                float2 uvOffset = i.uv + diameter / 2.0f;
                float2 index = floor(uvOffset / diameter);
                float2 xy = index * diameter;
                float dist = distance(i.uv, xy);

                clip(dimensions.z - dist);

                return color;
            }
            ENDCG
        }
    }
}