Lower resolution for raymarching object, HoloLens

Hi all!

I am doing a raymarching shader for Unity which works well but is slow. I am then trying to lower the resolution of the rendering ONLY for those objects (which is targeting a particular layer) to increase speed while not touching too much on the quality (the default screen resolution is high compared to my need).

I then created a camera which has for parent Camera.main, and which I attached this code:

Code (CSharp):

1.  
2. using UnityEngine;
3. using UnityEngine.XR;
4. public class RenderTextureCamera : MonoBehaviour
5. {
6.     /// <summary>
7.     /// The render texture use for volume rendering
8.     /// </summary>
9.     private RenderTexture m_volumeRenderingTexture = null;
10.     public Material CopyTextureMaterial;
11.     void Start()
12.     {
13.         //Create a render texture for the volume rendering camera. No depth texture, alpha component
14.         m_volumeRenderingTexture = new RenderTexture((int)(Camera.main.pixelWidth*0.75), (int)(Camera.main.pixelHeight*0.75), 0, RenderTextureFormat.ARGB32);
15.         m_volumeRenderingTexture.vrUsage = VRTextureUsage.TwoEyes;
16.         Camera camera = GetComponent<Camera>();
17.         int cullingMask = camera.cullingMask;
18.         float depth     = camera.depth;
19.         Color color     = camera.backgroundColor;
20.         camera.CopyFrom(Camera.main); //Copy stereoscopy parameters
21.         camera.cullingMask     = cullingMask; //Only my layer (in the editor)
22.         camera.backgroundColor = color; //(0,0,0,0) in the editor
23.         camera.depth = depth; //I do not know if this was important
24.         camera.clearFlags = CameraClearFlags.SolidColor;
25.         camera.targetTexture = m_volumeRenderingTexture;
26.         camera.rect = new Rect(0, 0, 1, 1);
27.     }
28.    
29.     private void OnPreRender()
30.     {
31.         Camera camera = GetComponent<Camera>();
32.         camera.targetTexture = m_volumeRenderingTexture;
33.     }
34.     private void OnPostRender()
35.     {
36.         Camera camera = GetComponent<Camera>();
37.         camera.targetTexture = null;
38.         Graphics.Blit(m_volumeRenderingTexture, (RenderTexture)null); //Should go on screen, right?
39.     }
40.  
41. }
42.  

However, for un unknown reason, this code does not work. I tried multiple things, and either my camera's rendering is not displayed, either the alpha component of my camera is not taken into account (I played with RenderTexture.active and camera.targetTexture parameters).

Is there a way to blend two cameras on screen, one after the other?

Best

 

For people asking how to overlay cameras: the issue was on OnRenderImage which does not use, by default, a transparency-proof material.

Here is my code:

Code (CSharp):

1.  
2. using UnityEngine;
3. using UnityEngine.XR;
4. public class RenderTextureCamera : MonoBehaviour
5. {
6.     /// <summary>
7.     /// The render texture use for volume rendering
8.     /// </summary>
9.     private RenderTexture m_volumeRenderingTexture = null;
10.  
11.     public Material CopyTextureMaterial;
12.  
13.     private Material m_material;
14.  
15.     void Start()
16.     {
17.         //Create a render texture for the volume rendering camera. No depth texture, alpha component
18.         m_volumeRenderingTexture = new RenderTexture(512, (int)(Camera.main.pixelHeight * 512.0f / Camera.main.pixelWidth), 16, RenderTextureFormat.ARGB32);
19.         m_volumeRenderingTexture.vrUsage = VRTextureUsage.TwoEyes;
20.  
21.         m_material = new Material(CopyTextureMaterial);
22.  
23.         Camera camera = GetComponent<Camera>();
24.         int cullingMask = camera.cullingMask;
25.         float depth = camera.depth;
26.         camera.CopyFrom(Camera.main);
27.         camera.cullingMask = cullingMask;
28.         camera.depth = depth;
29.         camera.backgroundColor = new Color(0, 0, 0, 0);
30.         camera.clearFlags = CameraClearFlags.SolidColor;
31.         camera.targetTexture = m_volumeRenderingTexture;
32.         camera.rect = new Rect(0, 0, 1, 1);
33.     }
34.  
35.     private void OnPreRender()
36.     {
37.         Camera camera = GetComponent<Camera>();
38.         camera.targetTexture = m_volumeRenderingTexture;
39.     }
40.  
41.     private void OnRenderImage(RenderTexture source, RenderTexture destination)
42.     {
43.         Graphics.Blit(source, destination, m_material); //The culprit! m_material is a stupid shader that uses alpha blending
44.     }
45.  
46.     private void OnPostRender()
47.     {
48.         Camera camera = GetComponent<Camera>();
49.         camera.targetTexture = null; //I guess this force the final rendering to be on the screen, without it, the camera never overlay
50.     }
51. }
52.  

 

Well, that was what I thought, until I test with stereoscopic display… My lower resolution camera does not appear in full screen for an unknown Reason.

My shader:

Code (CSharp):

1. Shader "Sereno/CopyTexture"
2. {
3.     Properties
4.     {
5.         _MainTex("Main Texture", any) = "" {}
6.     }
7.  
8.     SubShader
9.     {
10.         Tags{ "Queue" = "Transparent" "RenderType" = "Transparent" }
11.  
12.         Lighting Off
13.         Cull Off
14.         ZWrite Off
15.         Blend SrcAlpha OneMinusSrcAlpha
16.         Fog {Mode Off}
17.  
18.         Pass
19.         {
20.             CGPROGRAM
21.             #pragma vertex vert
22.             #pragma fragment frag
23.  
24.             #include "UnityCG.cginc"
25.  
26.             struct appdata
27.             {
28.                 float4 vertex : POSITION;
29.                 fixed4 color  : COLOR;
30.                 float2 uv     : TEXCOORD0;
31.                 UNITY_VERTEX_INPUT_INSTANCE_ID
32.             };
33.  
34.             struct v2f
35.             {
36.                 float4 vertex : SV_POSITION;
37.                 fixed4 color  : COLOR;
38.                 float2 uv     : TEXCOORD0;
39.                 UNITY_VERTEX_INPUT_INSTANCE_ID
40.                 UNITY_VERTEX_OUTPUT_STEREO
41.             };
42.  
43.             /** The texture data*/
44.             UNITY_DECLARE_SCREENSPACE_TEXTURE(_MainTex);
45.             //sampler2D _MainTex;
46.             uniform float4 _MainTex_ST; //Scale--translation of that texture
47.             uniform float2 _Scale = float2(1.0, 1.0);
48.  
49.             v2f vert(appdata v)
50.             {
51.                 v2f o;
52.                 UNITY_SETUP_INSTANCE_ID(v);
53.                 UNITY_TRANSFER_INSTANCE_ID(v, o);
54.                 UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
55.  
56.                 o.vertex = UnityObjectToClipPos(v.vertex);
57.                 o.color  = v.color;
58.                 o.uv     = TRANSFORM_TEX(v.uv, _MainTex);
59.                
60.                 return o;
61.             }
62.  
63.             fixed4  frag(v2f input) : COLOR
64.             {
65.                 UNITY_SETUP_INSTANCE_ID(input);
66.                 fixed4 color = UNITY_SAMPLE_SCREENSPACE_TEXTURE(_MainTex, input.uv);
67.                 //fixed4 color = tex2D(_MainTex, input.uv);
68.  
69.                 return color;
70.             }
71.             ENDCG
72.         }
73.     }
74. }
75.  

and my C# camera code:

Code (CSharp):

1.  
2. using UnityEngine;
3. using UnityEngine.XR;
4. public class RenderTextureCamera : MonoBehaviour
5. {
6.     /// <summary>
7.     /// The render texture use for volume rendering
8.     /// </summary>
9.     private RenderTexture m_volumeRenderingTexture = null;
10.  
11.     public Material CopyTextureMaterial;
12.  
13.     private Material m_material;
14.  
15.     void Start()
16.     {
17.         //Create a render texture for the volume rendering camera. No depth texture, alpha component
18.         m_volumeRenderingTexture = new RenderTexture(512, (int)(Screen.height * 512.0f / ((XRSettings.isDeviceActive ? 2 : 1)*Screen.width)), 16, RenderTextureFormat.ARGB32);
19.         m_volumeRenderingTexture.vrUsage = VRTextureUsage.TwoEyes;
20.  
21.         m_material = new Material(CopyTextureMaterial);
22.  
23.         Camera camera = GetComponent<Camera>();
24.         int cullingMask = camera.cullingMask;
25.         float depth = camera.depth;
26.         camera.CopyFrom(Camera.main);
27.         camera.cullingMask = cullingMask;
28.         camera.depth = depth;
29.         camera.backgroundColor = new Color(0, 0, 0, 0);
30.         camera.clearFlags = CameraClearFlags.Depth;
31.         camera.targetTexture = m_volumeRenderingTexture;
32.         camera.depthTextureMode = DepthTextureMode.None;
33.         camera.forceIntoRenderTexture = true;
34.     }
35.  
36.     private void OnPreRender()
37.     {
38.         Camera camera = GetComponent<Camera>();
39.         camera.targetTexture = m_volumeRenderingTexture;
40.     }
41.  
42.     private void OnRenderImage(RenderTexture source, RenderTexture destination)
43.     {
44.         Graphics.Blit(source, destination, m_material);
45.  
46.         //Graphics.SetRenderTarget(destination);
47.         //m_material.SetPass(0);
48.         //m_material.SetTexture("_MainTex", source);
49.  
50.         /*GL.PushMatrix();
51.         GL.LoadOrtho();
52.        
53.         GL.Begin(GL.QUADS);
54.             GL.TexCoord2(0, 0);
55.             GL.Vertex3(0, 0, 0);
56.             GL.TexCoord2(0, 1);
57.             GL.Vertex3(0, 1, 0);
58.             GL.TexCoord2(1, 1);
59.             GL.Vertex3(1, 1, 0);
60.             GL.TexCoord2(1, 0);
61.             GL.Vertex3(1, 0, 0);
62.         GL.End();
63.  
64.         GL.PopMatrix();*/
65.     }
66.  
67.     private void OnPostRender()
68.     {
69.         Camera camera = GetComponent<Camera>();
70.         camera.targetTexture = null;
71.         Graphics.Blit(m_volumeRenderingTexture, null as RenderTexture, m_material);
72.     }
73. }
74.  

 

Well, this issue is not possible to overcome according to https://forum.unity.com/threads/is-single-pass-stereo-rendering-supported-for-rendertextures.485294/
Using targetTexture in Unity breaks the stereoscopy for an unknown reason...