Change value of a shader propertie using a Slider

Questions & Answers
1

Hi I’ve looked at other answers similar to what I’m asking but i still need clarity on it.

How would you use a GUI slider to control say specular amount of a shader in game.

using UnityEngine;
using System.Collections;

public class ClickObject : MonoBehaviour {

Rect windowRect = new Rect(10, 20, 500,300 );
public bool canClick;
public GameObject cont;

//Toggle Booleans
bool toggleWindow;
bool toggleWindowTwo;
bool toggleWindowThree;
bool toggleWindowFour;
bool toggleWindowFive;

// Use this for initialization
void Start () {
	canClick = false;

	toggleWindow = false;
	toggleWindowTwo = false;
}

void OnGUI ()
{
	if(canClick)
	{

		ToggleWindows();

		if(Input.GetMouseButtonUp(0))
		{
			Ray ray = camera.ScreenPointToRay(Input.mousePosition);
			RaycastHit hit;

			if(Physics.Raycast(ray,out hit) && hit.transform.tag == "Object")
			{
				Debug.Log("Open Lambert Shader Window");
				toggleWindow = true;
			}
			else if(Physics.Raycast(ray,out hit) && hit.transform.tag == "Object2")
			{
				Debug.Log("Open Blinn Shader Window");
				toggleWindowTwo = true;
			}

		}

	}
	else
	{
		toggleWindow = false;
		toggleWindowTwo = false;
	}

	if(Input.GetKeyUp(KeyCode.Escape))
	{
		toggleWindow = false;
		toggleWindowTwo = false;
	}
}

void ToggleWindows ()
{
	if(toggleWindow)
	{
		GUI.Window(0, windowRect, DoMyWindow, "My Window");
		toggleWindowTwo = false;
	}
	else if(toggleWindowTwo)
	{
		GUI.Window(1, windowRect, DoMyWindowTwo, "My Window 2");
		toggleWindow = false;
	}
}

void DoMyWindow(int windowID) 
{
	float hSliderValue;
	float hSliderValue2=1.0f;
	float hSliderValue3=1.0f;
	float hSliderValue4=1.0f;
	float hSliderValue5=1.0f;
	float hSliderValue6=1.0f;
	float hSliderValue7=1.0f;
	float hSliderValue8=1.0f;
	float hSliderValue9=1.0f;
	float hSliderValue10=1.0f;
	float hSliderValue11=1.0f;




	//gets the shader
	

		// Animate the blend value

hSliderValue =	cont.renderer.material.SetFloat( "_BaseColour", hSliderValue );
		
		if (GUI.Button(new Rect(350, 30, 100, 20), "Shader 1"))
	{
		print("Tweak Values");

	}

	hSliderValue = GUI.HorizontalSlider (new Rect (25, 40, 100, 30), hSliderValue, 0.0f, 1.0f);
	GUI.Label (new Rect (150, 35, 100, 30), "Base Colour");
	hSliderValue2 = GUI.HorizontalSlider (new Rect (25, 60, 100, 30), hSliderValue2, 0.0f, 1.0f);
	GUI.Label (new Rect (150, 55, 100, 30), "Subsurface");
	hSliderValue3 = GUI.HorizontalSlider (new Rect (25, 80, 100, 30), hSliderValue3, 0.0f, 1.0f);
	GUI.Label (new Rect (150, 75, 100, 30), "Metallic");
	hSliderValue4 = GUI.HorizontalSlider (new Rect (25, 100, 100, 30), hSliderValue4, 0.0f, 1.0f);
	GUI.Label (new Rect (150, 95, 100, 30), "Specular");
	hSliderValue5 = GUI.HorizontalSlider (new Rect (25, 120, 100, 30), hSliderValue5, 0.0f, 1.0f);
	GUI.Label (new Rect (150, 115, 100, 30), "Specular Tint");
	hSliderValue6 = GUI.HorizontalSlider (new Rect (25, 140, 100, 30), hSliderValue6, 0.0f, 1.0f);
	GUI.Label (new Rect (150, 135, 100, 30), "Roughness");
	hSliderValue7 = GUI.HorizontalSlider (new Rect (25, 160, 100, 30), hSliderValue7, 0.0f, 1.0f);
	GUI.Label (new Rect (150, 155, 100, 30), "Anisotropic");
	hSliderValue8 = GUI.HorizontalSlider (new Rect (25, 180, 100, 30), hSliderValue8, 0.0f, 1.0f);
	GUI.Label (new Rect (150, 175, 100, 30), "Sheen");
	hSliderValue9 = GUI.HorizontalSlider (new Rect (25, 200, 100, 30), hSliderValue9, 0.0f, 1.0f);
	GUI.Label (new Rect (150, 195, 100, 30), "Sheen Tint");
	hSliderValue10 = GUI.HorizontalSlider (new Rect (25, 220, 100, 30), hSliderValue10, 0.0f, 1.0f);
	GUI.Label (new Rect (150, 215, 100, 30), "Clearcoat");
	hSliderValue11 = GUI.HorizontalSlider (new Rect (25, 240, 100, 30), hSliderValue11, 0.0f, 1.0f);
	GUI.Label (new Rect (150, 235, 100, 30), "Clearcoat Gloss");

}

void DoMyWindowTwo(int windowID) 
{
	if (GUI.Button(new Rect(10, 20, 100, 20), "Shader 2")){
		print("Tweak Values");
	}
}

}

2

See here for the GUI Slider (horizontal one anyway):

The value returned by the call (hSliderValue in the link above) can be stored in a variable. In the Update method, you can use this value to drive the shader (kind of like this):

float value;
float prevValue;

public GameObject shadedObject;

void  OnGUI() {
  value = GUI.HorizontalSlider(new Rect(25, 25, 100, 30), value, 0.0F, 10.0F);
}

void Update() {
  if (prevValue != value) {
    prevValue = value;
    shadedObject.renderer.sharedMaterial.SetFloat("myShaderSpec", value);
  }
}

Using sharedMaterial will modify every object in the scene that uses it. Use renderer.material if you just want to change a single object.

Unity Ref: