Question by Biggzlar · Sep 22, 2018 at 03:30 PM · shader programming cg glsl

Shaders are horrible. Why does the shader of one object affect the shader of the other object???

Basically this. I was trying to build an interactive plant shader. Nothing works because the documentation is a joke and I don't know anything about shaders.

Nevertheless, at one point I found out that changing the shader of the floor (a cube object) to something other than the default material, the plants (with the supposedly interactive shader applied) would move to a different position. WHAT?!

Interactive plant shader:

 Shader "Custom/plant_shader" {
     Properties {
     }
     SubShader {
         Tags { "RenderType"="Grass" }
         LOD 200
         
         CGPROGRAM
 
         #pragma surface surf Standard fullforwardshadows vertex:vert
         #pragma target 3.0
 
         sampler2D _HistoryTex;
         float4 _HistoryWorldPos;
         float4 _MainColor;
         half _HistoryScale;
 
         float4 tex;
 
         struct Input {
             float2 uv_HistoryTex;
         };
 
         float getHistoryWorldPos(appdata_full v, float4 vertex_position){
             float2 historyOffset = vertex_position.xz - _HistoryWorldPos.xz;
             float2 historyUV = historyOffset / _HistoryScale * 0.5f + 0.5f;
 
             tex = tex2Dlod(_HistoryTex, float4(historyUV, 0, 0));
             vertex_position.y -= tex.r * 2.4f * v.color.r;
 
             return vertex_position.y;
         }
 
         void vert(inout appdata_full v){
             float4 world_pos = mul(unity_ObjectToWorld, v.vertex);
             v.vertex.y = getHistoryWorldPos(v, world_pos);
         }
 
         void surf (Input IN, inout SurfaceOutputStandard o) {
             fixed4 c = tex2D (_HistoryTex, IN.uv_HistoryTex);
             o.Albedo = tex.rgb;
         }
         ENDCG
     }
     FallBack "Diffuse"
 }

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