Differences

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--- renderpass [2020/01/09 14:07] – [Render-Pass Material] admin
+++ renderpass [2020/01/09 14:07] – [Rendering Method] admin
@@ Line 31: / Line 31: @@
 In the next step you have to decide, if a **one-for-all material shader** should be used //or// the **object specific material shaders**.
 Because sometimes you want the full scene just to be rendered from another perspective (like reflection) or you want to store a specific value (like the depth-value in shadow mapping) in the FBO.
+===== Render-Pass Material =====
+To create an individual material shader for your render-pass you need to extend **TGorillaRenderPassMaterialSource** and **TGorillaRenderPassMaterial**.
+<file pascal>
+uses
+  FMX.Types3D,
+  FMX.Materials,
+  FMX.MaterialSources,
+  Gorilla.Controller;
+  TMyRenderPassMaterial = class(TGorillaRenderPassMaterial)
+    protected
+      procedure DoApply(const Context: TContext3D); override;
+      procedure DoInitialize(); override;
+    public
+  end;
+  TMyRenderPassMaterialSource = class(TGorillaRenderPassMaterialSource)
+    protected
+      function CreateMaterial() : TMaterial; override;
+    public
+  end;
+</file>
+Here you can have a look at this example of a render-pass material implementation.
+Notice: No multiple targets used here. We just write to default output buffer by gl_FragColor.
+<file pascal>
+uses
+  Gorilla.Context.GLES;
+  ResourceString SOURCE_VS =
+    'attribute vec3 a_Position;' +
+    '' +
+    'uniform mat4 _ModelViewProjMatrix;' +
+    '' +
+    'varying vec4 v_position;' +
+    '' +
+    'void main( void ){' +
+    '  vec4 fvPosition = vec4(a_Position.x, a_Position.y, a_Position.z, 1.0);' +
+    '  v_position = _ModelViewProjMatrix * fvPosition;' +
+    '  gl_Position = v_position;' +
+    '}';
+  ResourceString SOURCE_FS =
+    'varying vec4 v_position;' +
+    '' +
+    'void main( void ){' +
+    '  gl_FragColor = v_position;' +
+    '}';
+procedure TMyRenderPassMaterial.DoInitialize();
+var LOGLBytes : TArray<Byte>;
+begin
+  LOGLBytes := TEncoding.ASCII.GetBytes(SOURCE_VS);
+  FVertexShader := TShaderManager.RegisterShaderFromData('MyRenderPass.fvs', TContextShaderKind.VertexShader, '', [
+    TContextShaderSource.Create(TContextShaderArch.GLSL,
+      LOGLBytes,
+      [
+      TContextShaderVariable.Create('ModelViewProjMatrix', TContextShaderVariableKind.Matrix, 0, 4)
+      ]
+    )
+  ]);
+  LOGLBytes := TEncoding.ASCII.GetBytes(SOURCE_FS);
+  FPixelShader := TShaderManager.RegisterShaderFromData('MyRenderPass.fps', TContextShaderKind.PixelShader, '', [
+    TContextShaderSource.Create(TContextShaderArch.GLSL,
+      LOGLBytes,
+      []
+    )
+  ]);
+end;
+{ TMyRenderPassMaterial }
+procedure TMyRenderPassMaterial.DoApply(const Context: TContext3D);
+begin
+  // activate shaders
+  Context.SetShaders(FVertexShader, FPixelShader);
+  // set model view projection matrix
+  TCustomContextOpenGL(Context).SetShaderVariable('ModelViewProjMatrix', Context.CurrentModelViewProjectionMatrix, true);
+end;
+{ TMyRenderPassMaterialSource }
+function TMyRenderPassMaterialSource.CreateMaterial() : TMaterial;
+begin
+  Result := TMyRenderPassMaterial.Create(Self);
+end;
+</file>
+You than have to overwrite the CreateMaterialSource() method and create your material source.
+In case you'd like to use the element specific material shaders, return nil in the CreateMaterialSource() method.
+<file pascal>
+function TMyRenderPass.CreateMaterialSource() : TGorillaRenderPassMaterialSource;
+begin
+  result := TMyRenderPassMaterialSource.Create(Self);
+end;
+</file>
 ===== Start / End =====