Changing the Sprite Renderer's Color property has no effect in my Custom Shader

Tdebel, what you are doing here in the vertex shader is actually using the color of the material tint, rather than the color of the SpriteRenderer.

appdata_full should have a field "appdata_full.color" that needs to be fed into the "Input" struct's "color" field, instead of using the "_Color" argument. This will use the SpriteRenderer's color as applied to the vertices.

I'm having the same problem, did you manage to solve this Tdebel?

EDIT: I managed to solve it! I'm posting it here in case anyone's stuck like me.

My code looks a little different to Tdebel's above, but maybe the same principle applies? In my code I had tried to access the standard color in my Sprite Renderer (on an object with a custom shader) a little something like this:

 //A renderer I pulled into the code through the editor
 public SpriteRenderer myRenderer;
     
     
 private void ChangeColor()  {
         myRenderer.material.color = Color.blue
 }

This didn't change the color or alpha for me. What worked instead was if I removed the material-call and just went straight for color like this:

 private void ChangeColor()  {
         myRenderer.color = Color.blue
 }

Hope this helps someone in the future!

The color property on SpriteRenderer is what's called an Instanced Property, which are changed using a MaterialPropertyBlock, which allows the Material's Instanced Properties to be changed without requiring a new SetPass call / batch. This page from the docs references that:

A Sprite Renderer uses the texture supplied in the Sprite property but uses the shader and other properties from the Material property (this is actually accomplished using a MaterialPropertyBlock behind the scenes). This means that you can use the same material to render different sprites without worrying about which texture is assigned on the material.

---

If you're unfamiliar with MaterialPropertyBlock or Instanced Properties in shaders, then I recommend this excellent tutorial. I'm still learning myself, and it's a confusing landscape out there with Unity having different information in various places, some of it outdated, much of it incomplete, etc.

Anyway, looking at the way Unity does it in their shader (I'm not sure how up to date that code is, but it can at least give hints), it looks like they're referencing a reserved variable named unity_SpriteRendererColorArray, so it appears you need to tap into that.

Adding/modifying this code to my shader worked for me (goes inside the CGPROGRAM, see the comments):

 // setup instanced property
 UNITY_INSTANCING_BUFFER_START(MyProps)
     UNITY_DEFINE_INSTANCED_PROP(fixed4, unity_SpriteRendererColorArray)
 UNITY_INSTANCING_BUFFER_END(MyProps)
 
 struct appdata
 {
     float4 vertex : POSITION;
     fixed4 color : COLOR; // apparently must be fixed4 to work with instancing
     float2 uv : TEXCOORD0;
     UNITY_VERTEX_INPUT_INSTANCE_ID // store instanced ID
 };
 
 struct v2f
 {
     float4 vertex : SV_POSITION;
     fixed4 color : COLOR;
     float2 uv : TEXCOORD0;
 };
 
 v2f vert (appdata v)
 {
     v2f o;
     UNITY_SETUP_INSTANCE_ID(v); // setup instanced id
     o.vertex = UnityObjectToClipPos(v.vertex);
     o.uv = v.uv;
     // get the instanced property
     o.color = v.color * UNITY_ACCESS_INSTANCED_PROP(MyProps, unity_SpriteRendererColorArray);
 
     return o;
 }

p.s. (meta) I'm a newb and can't apparently figure out how to break text into paragraphs without resorting to a horizontal rule. Anyone have a solution for that?