feat(shader): add logarithmic depth (#346)

* feat(shader): add logarithmic depth

samples/render/Sample_HighPrecision.ts

@@ -0,0 +1,78 @@
+import { Engine3D, Scene3D, AtmosphericComponent, View3D, CameraUtil, HoverCameraController, Object3D, MeshRenderer, SphereGeometry, UnLitMaterial, BoxGeometry, SkyRenderer, Color } from "@orillusion/core";
+import { GUIHelp } from "@orillusion/debug/GUIHelp";
+import { GUIUtil } from "@samples/utils/GUIUtil";
+
+export class Sample_HighPrecision {
+
+    async run() {
+        Engine3D.setting.render.useLogDepth = true;
+
+        await Engine3D.init();
+
+        let scene = new Scene3D();
+
+        GUIHelp.init();
+
+        let camera = CameraUtil.createCamera3DObject(scene);
+        camera.perspective(60, Engine3D.aspect, 1.0, 6000 * 10000.0);
+        camera.object3D.z = 3;
+
+        let cameraController = camera.object3D.addComponent(HoverCameraController);
+        cameraController.setCamera(20, -45, 1500 * 10000.0);
+        cameraController.minDistance = 601 * 10000.0;
+        cameraController.maxDistance = 6000 * 10000.0;
+
+        this.initScene(scene);
+
+        let view = new View3D();
+        view.scene = scene;
+        view.camera = camera;
+        Engine3D.startRenderView(view);
+    }
+
+    async initScene(scene: Scene3D) {
+        {
+            let obj = new Object3D();
+            obj.rotationX = -90;
+            let mr = obj.addComponent(MeshRenderer);
+            mr.geometry = new SphereGeometry(600 * 10000.0, 128, 128);
+            let mat = new UnLitMaterial();
+            mat.baseMap = await Engine3D.res.loadTexture('textures/earth/8k_earth_daymap.jpg');
+            mr.material = mat;
+            scene.addChild(obj);
+        }
+
+        {
+            let obj = new Object3D();
+            obj.x = 600 * 10000.0;
+            let mr = obj.addComponent(MeshRenderer);
+            mr.geometry = new BoxGeometry(600 * 10000.0, 100 * 10000.0, 100 * 10000.0);
+            let mat = new UnLitMaterial();
+            mat.baseColor = new Color(1, 0, 0)
+            mr.material = mat;
+            scene.addChild(obj);
+        }
+
+        {
+            let obj = new Object3D();
+            obj.y = 600 * 10000.0;
+            let mr = obj.addComponent(MeshRenderer);
+            mr.geometry = new BoxGeometry(100 * 10000.0, 600 * 10000.0, 100 * 10000.0);
+            let mat = new UnLitMaterial();
+            mat.baseColor = new Color(0, 1, 0)
+            mr.material = mat;
+            scene.addChild(obj);
+        }
+
+        {
+            let obj = new Object3D();
+            obj.z = 600 * 10000.0;
+            let mr = obj.addComponent(MeshRenderer);
+            mr.geometry = new BoxGeometry(100 * 10000.0, 100 * 10000.0, 600 * 10000.0);
+            let mat = new UnLitMaterial();
+            mat.baseColor = new Color(0, 0, 1)
+            mr.material = mat;
+            scene.addChild(obj);
+        }
+    }
+}

src/assets/shader/core/base/Common_frag.ts

@@ -31,7 +31,7 @@ export let Common_frag: string = /*wgsl*/ `
 
     #if USE_OUTDEPTH
       #if USE_LOGDEPTH
-        ORI_FragmentOutput.out_depth = log2Depth(ORI_VertexVarying.fragCoord.z,globalUniform.near,globalUniform.far) ;
+        ORI_FragmentOutput.out_depth = log2DepthFixPersp(ORI_VertexVarying.fragPosition.w, globalUniform.near, globalUniform.far);
       #else
         ORI_FragmentOutput.out_depth = ORI_ShadingInput.FragDepth ;
       #endif

src/assets/shader/core/struct/VertexAttributes.ts

@@ -139,6 +139,10 @@ export let VertexAttributes: string = /*wgsl*/ `
     var viewPosition = ORI_MATRIX_V * worldPos;
     var clipPosition = ORI_MATRIX_P * viewPosition ;
 
+    #if USE_LOGDEPTH
+        clipPosition.z = log2Depth(clipPosition.w, globalUniform.near, globalUniform.far);
+    #endif
+
     ORI_CameraWorldDir = normalize(ORI_CAMERAMATRIX[3].xyz - worldPos.xyz) ;
 
     ORI_VertexOut.index = f32(vertex.index) ;

src/assets/shader/math/MathShader.ts

@@ -192,12 +192,20 @@ fn dir_to_faceId(pt:vec3<f32>) -> i32 {
       return log2(depth + 1.0) * 2.0 / (log(far + 1.0) / 0.6931471805599453) * 0.5;
     }
 
-    fn log2Depth(depth : f32, near:f32, far:f32) -> f32 {
-      let pt = pow((far / near),depth);
-      return near * pt / (far / near);
+    fn log2Depth(depth:f32, near:f32, far:f32) -> f32 {
+      let Fcoef:f32 = 2.0 / log2(far + 1.0);
+      var result:f32 = (log2(max(1e-6, 1.0 + depth)) * Fcoef - 1.0);
+      result = (1.0 + result) / 2.0;
+      return result * depth;
     }
 
-   
+    fn log2DepthFixPersp(depth:f32, near:f32, far:f32) -> f32 {
+      let flogz:f32 = 1.0 + depth;
+      let Fcoef_half:f32 = (2.0 / log2(far + 1.0)) * 0.5;
+      var result:f32 = log2(flogz) * Fcoef_half;
+      result = (1.0 + result) / 2.0;
+      return result;
+    }
 
 
     fn QuaternionToMatrix(q: vec4<f32>) -> mat4x4<f32> {