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Question by C_So · Oct 07, 2019 at 06:35 PM · rendertexturegl

Rendering with GL.Begin to a RenderTexture does not update it continuously (2019.2)

So I am trying to render a trianglestrip to a rendertexture. For this I created a small script that takes a bunch of transforms and a rendertexture and draws a trianglestrip that connects the transforms. For simplicity, I assume the transforms are already in UVspace and use an identity matrix.

 public class GLRenderTextureTest : MonoBehaviour {
     public List<Transform> targets;
     public RenderTexture rt;
     private Material UVMaterial;
 
     void Start() {
         UVMaterial = new Material(Shader.Find("Unlit/TestShader"));
     }
     
     void Update() {
         RenderTexture.active = rt;
         UVMaterial.SetPass(0);
 
         GL.PushMatrix();
         GL.LoadIdentity();
 
         GL.Begin(GL.TRIANGLE_STRIP);
 
         for (int i = 0; i < targets.Count; i++) {
             GL.Vertex3(targets[i].position.x, targets[i].position.z, 0);
         }
 
         GL.End();
         GL.PopMatrix();
 
         RenderTexture.active = null;
     }
 }


And this is what it looks like in the scene: alt text

But if I then go and move one of the transforms, the rendertexture does not update! alt text

I feel like this should be working. I've already exhausted all solutions the google search results provided, to no avail. So here I am, stuck with a simple task, not knowing how to fix this.

To reproduce:

  1. Create a new 3D project.

  2. Create a new RenderTexture RT, no depth buffer, size 1024x1024

  3. Create a new Material M

  4. Add RenderTexture RT to Material M

  5. Create a new Unlit Shader and name it TestShader

  6. Add a quad to the scene, rotate by 90° x, scale 2, pos in zero

  7. Add Material M to Quad

  8. Add 8 (or any x >=3) spheres to the scene, scale 0,05f, place them inside the quad area

  9. Add a new script called GLRenderTextureTest, copy code from above

  10. Add spheres and rendertexture to the script in inspector

  11. save scene

  12. hit play and move any sphere

screenshot2.png (12.7 kB)
screenshot1.png (14.6 kB)
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