Fix procedural sky with orthographic camera

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -77,6 +77,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fix for lookdev toggling renderers that are set to non editable or are hidden in the inspector.
 - Fixed issue with mipmap debug mode not properly resetting full screen mode (and viceversa). 
 - Added unsupported message when using tile debug mode with MSAA.
+- Fix procedural sky with orthographic camera (case 1278013).
 
 ### Changed
 - Preparation pass for RTSSShadows to be supported by render graph.

com.unity.render-pipelines.high-definition/Runtime/Material/Fabric/IBLFilterCharlie.cs

@@ -66,7 +66,7 @@ void FilterCubemapCommon(CommandBuffer cmd,
                     for (int face = 0; face < 6; ++face)
                     {
                         var faceSize = new Vector4(source.width >> mip, source.height >> mip, 1.0f / (source.width >> mip), 1.0f / (source.height >> mip));
-                        var transform = HDUtils.ComputePixelCoordToWorldSpaceViewDirectionMatrix(0.5f * Mathf.PI, Vector2.zero, faceSize, worldToViewMatrices[face], true);
+                        var transform = HDUtils.ComputePixelCoordToWorldSpaceViewDirectionMatrix(false, 0.5f * Mathf.PI, Vector2.zero, faceSize, worldToViewMatrices[face], true);
 
                         props.SetMatrix(HDShaderIDs._PixelCoordToViewDirWS, transform);
 

com.unity.render-pipelines.high-definition/Runtime/Material/GGXConvolution/IBLFilterGGX.cs

@@ -149,7 +149,7 @@ void FilterCubemapCommon(CommandBuffer cmd,
                     for (int face = 0; face < 6; ++face)
                     {
                         var faceSize = new Vector4(source.width >> mip, source.height >> mip, 1.0f / (source.width >> mip), 1.0f / (source.height >> mip));
-                        var transform = HDUtils.ComputePixelCoordToWorldSpaceViewDirectionMatrix(0.5f * Mathf.PI, Vector2.zero, faceSize, worldToViewMatrices[face], true);
+                        var transform = HDUtils.ComputePixelCoordToWorldSpaceViewDirectionMatrix(false, 0.5f * Mathf.PI, Vector2.zero, faceSize, worldToViewMatrices[face], true);
 
                         props.SetMatrix(HDShaderIDs._PixelCoordToViewDirWS, transform);
 

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Camera/HDCamera.cs

@@ -1330,7 +1330,7 @@ Matrix4x4 ComputePixelCoordToWorldSpaceViewDirectionMatrix(ViewConstants viewCon
             }
             Vector2 lensShift = camera.GetGateFittedLensShift();
 
-            return HDUtils.ComputePixelCoordToWorldSpaceViewDirectionMatrix(verticalFoV, lensShift, resolution, viewConstants.viewMatrix, false, aspect);
+            return HDUtils.ComputePixelCoordToWorldSpaceViewDirectionMatrix(camera.orthographic, verticalFoV, lensShift, resolution, viewConstants.viewMatrix, false, aspect);
         }
 
         void Dispose()

com.unity.render-pipelines.high-definition/Runtime/RenderPipeline/Utility/HDUtils.cs

@@ -155,45 +155,62 @@ internal static void NextOverlayCoord(ref float x, ref float y, float overlayWid
         internal static float ProjectionMatrixAspect(in Matrix4x4 matrix)
             => -matrix.m11 / matrix.m00;
 
-        internal static Matrix4x4 ComputePixelCoordToWorldSpaceViewDirectionMatrix(float verticalFoV, Vector2 lensShift, Vector4 screenSize, Matrix4x4 worldToViewMatrix, bool renderToCubemap, float aspectRatio = -1)
+        internal static Matrix4x4 ComputePixelCoordToWorldSpaceViewDirectionMatrix(bool isOrthographic, float verticalFoV, Vector2 lensShift, Vector4 screenSize, Matrix4x4 worldToViewMatrix, bool renderToCubemap, float aspectRatio = -1)
         {
-            aspectRatio = aspectRatio < 0 ? screenSize.x * screenSize.w : aspectRatio;
+            Matrix4x4 result;
 
-            // Compose the view space version first.
-            // V = -(X, Y, Z), s.t. Z = 1,
-            // X = (2x / resX - 1) * tan(vFoV / 2) * ar = x * [(2 / resX) * tan(vFoV / 2) * ar] + [-tan(vFoV / 2) * ar] = x * [-m00] + [-m20]
-            // Y = (2y / resY - 1) * tan(vFoV / 2)      = y * [(2 / resY) * tan(vFoV / 2)]      + [-tan(vFoV / 2)]      = y * [-m11] + [-m21]
+            if (isOrthographic)
+            {
+                // Goal: find M, s.t. M * P = -F, where P is the pixel coord vector and F is direction of the focal axis of the camera in the world space.
+                // -F = (V)^-1 * [0,0,1,0]^T, where V is the world-to-view matrix.
+                // -F = (R * T)^-1 * [0,0,1,0]^T = (T^-1) * (R^-1) * [0,0,1,0]^T = (T^-1) * (R^T) * [0,0,1,0]^T.
+                Vector3 negF = worldToViewMatrix.GetRow(2);
 
-            float tanHalfVertFoV = Mathf.Tan(0.5f * verticalFoV);
+                result = Matrix4x4.zero;
+                result.SetColumn(3, new Vector4(negF.x, negF.y, negF.z, 1));
+            }
+            else
+            {
+                aspectRatio = aspectRatio < 0 ? screenSize.x * screenSize.w : aspectRatio;
 
-            // Compose the matrix.
-            float m21 = (1.0f - 2.0f * lensShift.y) * tanHalfVertFoV;
-            float m11 = -2.0f * screenSize.w * tanHalfVertFoV;
+                // Compose the view space version first.
+                // V = -(X, Y, Z), s.t. Z = 1,
+                // X = (2x / resX - 1) * tan(vFoV / 2) * ar = x * [(2 / resX) * tan(vFoV / 2) * ar] + [-tan(vFoV / 2) * ar] = x * [-m00] + [-m20]
+                // Y = (2y / resY - 1) * tan(vFoV / 2)      = y * [(2 / resY) * tan(vFoV / 2)]      + [-tan(vFoV / 2)]      = y * [-m11] + [-m21]
 
-            float m20 = (1.0f - 2.0f * lensShift.x) * tanHalfVertFoV * aspectRatio;
-            float m00 = -2.0f * screenSize.z * tanHalfVertFoV * aspectRatio;
+                float tanHalfVertFoV = Mathf.Tan(0.5f * verticalFoV);
 
-            if (renderToCubemap)
-            {
-                // Flip Y.
-                m11 = -m11;
-                m21 = -m21;
-            }
+                // Compose the matrix.
+                float m21 = (1.0f - 2.0f * lensShift.y) * tanHalfVertFoV;
+                float m11 = -2.0f * screenSize.w * tanHalfVertFoV;
 
-            var viewSpaceRasterTransform = new Matrix4x4(new Vector4(m00, 0.0f, 0.0f, 0.0f),
-                    new Vector4(0.0f, m11, 0.0f, 0.0f),
-                    new Vector4(m20, m21, -1.0f, 0.0f),
-                    new Vector4(0.0f, 0.0f, 0.0f, 1.0f));
+                float m20 = (1.0f - 2.0f * lensShift.x) * tanHalfVertFoV * aspectRatio;
+                float m00 = -2.0f * screenSize.z * tanHalfVertFoV * aspectRatio;
 
-            // Remove the translation component.
-            var homogeneousZero = new Vector4(0, 0, 0, 1);
-            worldToViewMatrix.SetColumn(3, homogeneousZero);
+                if (renderToCubemap)
+                {
+                    // Flip Y.
+                    m11 = -m11;
+                    m21 = -m21;
+                }
+
+                var viewSpaceRasterTransform = new Matrix4x4(new Vector4(m00, 0.0f, 0.0f, 0.0f),
+                        new Vector4(0.0f, m11, 0.0f, 0.0f),
+                        new Vector4(m20, m21, -1.0f, 0.0f),
+                        new Vector4(0.0f, 0.0f, 0.0f, 1.0f));
 
-            // Flip the Z to make the coordinate system left-handed.
-            worldToViewMatrix.SetRow(2, -worldToViewMatrix.GetRow(2));
+                // Remove the translation component.
+                var homogeneousZero = new Vector4(0, 0, 0, 1);
+                worldToViewMatrix.SetColumn(3, homogeneousZero);
+
+                // Flip the Z to make the coordinate system left-handed.
+                worldToViewMatrix.SetRow(2, -worldToViewMatrix.GetRow(2));
+
+                result = worldToViewMatrix.transpose * viewSpaceRasterTransform;
+            }
 
             // Transpose for HLSL.
-            return Matrix4x4.Transpose(worldToViewMatrix.transpose * viewSpaceRasterTransform);
+            return Matrix4x4.Transpose(result);
         }
 
         internal static float ComputZPlaneTexelSpacing(float planeDepth, float verticalFoV, float resolutionY)

com.unity.render-pipelines.high-definition/Runtime/Sky/SkyManager.cs

@@ -288,7 +288,7 @@ public void Build(HDRenderPipelineAsset hdAsset, RenderPipelineResources default
                 var lookAt = Matrix4x4.LookAt(Vector3.zero, CoreUtils.lookAtList[i], CoreUtils.upVectorList[i]);
                 var worldToView = lookAt * Matrix4x4.Scale(new Vector3(1.0f, 1.0f, -1.0f)); // Need to scale -1.0 on Z to match what is being done in the camera.wolrdToCameraMatrix API. ...
 
-                m_facePixelCoordToViewDirMatrices[i] = HDUtils.ComputePixelCoordToWorldSpaceViewDirectionMatrix(0.5f * Mathf.PI, Vector2.zero, m_CubemapScreenSize, worldToView, true);
+                m_facePixelCoordToViewDirMatrices[i] = HDUtils.ComputePixelCoordToWorldSpaceViewDirectionMatrix(false, 0.5f * Mathf.PI, Vector2.zero, m_CubemapScreenSize, worldToView, true);
                 m_CameraRelativeViewMatrices[i] = worldToView;
             }