Hello everyone, I’m back again after finishing the bloom, I’d thought I’d go after Kawase’s Light Streak Filter but I decided to implement something else while I continue figuring it out. John chapman has posted this great tutorial and I’m stuck on the first part 
Problem #1
[FIXED] Problem was C# code, I forgot when using a float4 it must be material.SetVector new Vector4
He uses the “noperspective” command which i’m not very familiar with to downscale and threshold the main image. I don’t really know if i’m doing this right I’m still a beginner. Here is what I have so far… I will most likely need help until the shader is finished, I hope i’m not asking for too much.
Problem #2
uScale doesn’t scale the image still. Multiplying it by “i.uv” works but I’m not sure if thats what I should be multiplying it by or the result that i’m looking for.
Problem#3
Calculating screen texture coordinates in CG/HLSL similar problem here:
float2 texelSize = 1.0 / float2(textureSize(_MainTex, 0);
Problem#4
Screen Aligned Quad in Unity for a post processing framework? Still a beginner trying to take on something more advanced but thats how you learn right?
Current CG Code:
Lens Flare
Shader "Custom/Per-Pixel Lens Flare" {
Properties
{
_MainTex ("Base (RGB)", 2D) = "white" {}
}
SubShader
{
Pass
{
CGPROGRAM
#pragma vertex vert_img
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest
#pragma target 3.0
#include "UnityCG.cginc"
uniform sampler2D _MainTex;
uniform float4 _uLensColor;
uniform float _uDispersal;
uniform float _uHaloWidth;
uniform float _uDistortion;
uniform int _uSamples;
uniform float _HorizontalSize;
//--------------Distortion Function---------------------------------------*/
float4 texDistorted(in sampler2D tex, in float2 texcoord, in float2 direction, in float3 distortion)
{
return float4(tex2D(tex, texcoord + direction * distortion.r).r,
tex2D(tex, texcoord + direction * distortion.g).g,
tex2D(tex, texcoord + direction * distortion.b).b, 1.0);
}
//----------------------------------------------------------------------------*/
float4 frag(v2f_img i) : COLOR
{
float2 texcoord = -i.uv + float2(1.0, 1.0); //Flip the texcoordinates
float2 texelSize = 1.0 / _HorizontalSize;
float2 ghostVec = (float2(0.5, 0.5) - texcoord) * _uDispersal;
float2 haloVec = normalize(ghostVec) * _uHaloWidth;
float3 distortion = float3(-texelSize.x * _uDistortion, 0.0, texelSize.x * _uDistortion);
//sample ghost
//unroll (8)]
float4 result = float4(0, 0, 0, 0);
for (int i = 0; i < 8; i++)
{
float2 offset = frac(texcoord + ghostVec * float(i));
float weight = length(float2(0.5, 0.5) - offset) / length(float2(0.5, 0.5));
weight = pow(1.0 - weight, 10.0);
result += texDistorted(_MainTex, offset, normalize(ghostVec), distortion) * weight;
}
float2 thistex = length(float2(0.5, 0.5) - texcoord) / length(float2(0.5, 0.5));
result *= _uLensColor;
//sample halo
half thislength = length(float2(0.5, 0.5) - frac(texcoord + haloVec));
float weight = thislength / length(float2(0.5, 0.5));
weight = pow(1.0 - weight, 10.0);
result += texDistorted(_MainTex, frac(texcoord + haloVec), normalize(ghostVec), distortion) * weight;
return result;
}
ENDCG
}
}
}
Bright Pass Filter
Shader "Custom/BrightPassFilter" {
Properties {
_MainTex ("Base (RGB)", 2D) = "white" {}
_uScale ("", Range(0.0,1.0)) = 1.0
_uBias ("", Range(0.0,1.0)) = 1.0
}
SubShader
{
Pass
{
CGPROGRAM
#pragma vertex vert_img
#pragma fragment frag
#pragma fragmentoption ARB_precision_hint_fastest
#pragma target 4.0
#include "UnityCG.cginc"
uniform sampler2D _MainTex;
uniform float4 _uScale;
uniform float4 _uBias;
//struct v2p
//{
// noperspective float2 vTexcoord : TEXCOORD0;
//};
//struct result
//{
// float4 fResult : COLOR;
//};
//void main(in v2p IN, out result OUT)
//{
//OUT.fResult = max(float4(0,0,0,0), tex2D(_MainTex, IN.vTexcoord) + _uBias) * _uScale;
//}
float4 frag(v2f_img i) : COLOR
{
float4 result = max(float4(0,0,0,0), tex2D(_MainTex, i.uv * _uScale) + _uBias);
return result;
}
ENDCG
}
}
}
Current C# Code:
using UnityEngine;
using System.Collections;
[ExecuteInEditMode]
public class ScreenSpaceLensFlare : MonoBehaviour {
#region Variables
public Shader BrightPassFilterShader;
public Shader LensFlareShader;
public float Threshold = 0.0f;
public int Downsampling = 1;
public Color LensColor;
public float HaloWidth = 1.0f;
public float Dispersal = 1.0f;
public float Distortion = 1.0f;
private Material BrightPassFilterMaterial;
private Material LensFlareMaterial;
#endregion
#region Properties
Material ThresholdMaterial
{
get
{
if(BrightPassFilterMaterial == null)
{
BrightPassFilterMaterial = new Material(BrightPassFilterShader);
BrightPassFilterMaterial.hideFlags = HideFlags.HideAndDontSave;
}
return BrightPassFilterMaterial;
}
}
Material PerPixelFlareMaterial
{
get
{
if(LensFlareMaterial == null)
{
LensFlareMaterial = new Material(LensFlareShader);
LensFlareMaterial.hideFlags = HideFlags.HideAndDontSave;
}
return LensFlareMaterial;
}
}
#endregion
// Use this for initialization
void Start ()
{
if(!SystemInfo.supportsImageEffects)
{
enabled = false;
return;
}
}
void OnRenderImage (RenderTexture sourceTexture, RenderTexture destTexture)
{
if(BrightPassFilterShader LensFlareShader != null)
{
//Step #1: Downsample screen, extract bright parts
RenderTexture Extract = RenderTexture.GetTemporary(Screen.width, Screen.height, 0);
ThresholdMaterial.SetVector("_uScale", new Vector4 (Downsampling, Downsampling, Downsampling, Downsampling));
ThresholdMaterial.SetVector("_uBias", new Vector4 (Threshold, Threshold, Threshold, Threshold));
Graphics.Blit(sourceTexture, Extract, ThresholdMaterial);
//Step #2: Render Lens flare on Screen
PerPixelFlareMaterial.SetFloat("_HorizontalSize", Screen.width);
PerPixelFlareMaterial.SetFloat("_uHaloWidth", HaloWidth);
PerPixelFlareMaterial.SetFloat("_uDistortion", Distortion);
PerPixelFlareMaterial.SetFloat("_uDispersal", Dispersal);
//PerPixelFlareMaterial.SetColor("_uLensColor", LensColor);
Graphics.Blit(Extract, destTexture, PerPixelFlareMaterial);
RenderTexture.ReleaseTemporary(Extract);
}
}
// Update is called once per frame
void Update ()
{
Threshold = Mathf.Clamp(Threshold, -1.0f, 0.0f);
}
void OnDisable ()
{
if(BrightPassFilterMaterial LensFlareMaterial)
{
DestroyImmediate(BrightPassFilterMaterial);
}
}
}
Its doing something at least
