Project skybox without perspective for ortho cameras

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

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Changed
 - Removed the material pass probe volumes evaluation mode.
 - Updated the tooltip for the Decal Angle Fade property (requires to enable Decal Layers in both HDRP asset and Frame settings) (case 1308048).
+- Fixed skybox for ortho cameras.
 
 ## [11.0.0] - 2020-10-21
 

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

@@ -1385,7 +1385,7 @@ Matrix4x4 ComputePixelCoordToWorldSpaceViewDirectionMatrix(ViewConstants viewCon
             }
             Vector2 lensShift = camera.GetGateFittedLensShift();
 
-            return HDUtils.ComputePixelCoordToWorldSpaceViewDirectionMatrix(verticalFoV, lensShift, resolution, viewConstants.viewMatrix, false, aspect);
+            return HDUtils.ComputePixelCoordToWorldSpaceViewDirectionMatrix(verticalFoV, lensShift, resolution, viewConstants.viewMatrix, false, aspect, camera.orthographic);
         }
 
         void Dispose()

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

@@ -140,35 +140,49 @@ internal static int GetRuntimeDebugPanelWidth(HDCamera hdCamera)
         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(float verticalFoV, Vector2 lensShift, Vector4 screenSize, Matrix4x4 worldToViewMatrix, bool renderToCubemap, float aspectRatio = -1, bool isOrthographic = false)
         {
-            aspectRatio = aspectRatio < 0 ? screenSize.x * screenSize.w : aspectRatio;
+            Matrix4x4 viewSpaceRasterTransform;
 
-            // 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)
+            {
+                // For ortho cameras, project the skybox with no perspective
+                // the same way as builtin does (case 1264647)
+                viewSpaceRasterTransform = new Matrix4x4(
+                    new Vector4(-2.0f * screenSize.z, 0.0f, 0.0f, 0.0f),
+                    new Vector4(0.0f, -2.0f * screenSize.w, 0.0f, 0.0f),
+                    new Vector4(1.0f, 1.0f, -1.0f, 0.0f),
+                    new Vector4(0.0f, 0.0f, 0.0f, 0.0f));
+            }
+            else
+            {
+                // 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 tanHalfVertFoV = Mathf.Tan(0.5f * verticalFoV);
+                aspectRatio = aspectRatio < 0 ? screenSize.x * screenSize.w : aspectRatio;
+                float tanHalfVertFoV = Mathf.Tan(0.5f * verticalFoV);
 
-            // Compose the matrix.
-            float m21 = (1.0f - 2.0f * lensShift.y) * tanHalfVertFoV;
-            float m11 = -2.0f * screenSize.w * tanHalfVertFoV;
+                // Compose the matrix.
+                float m21 = (1.0f - 2.0f * lensShift.y) * tanHalfVertFoV;
+                float m11 = -2.0f * screenSize.w * tanHalfVertFoV;
 
-            float m20 = (1.0f - 2.0f * lensShift.x) * tanHalfVertFoV * aspectRatio;
-            float m00 = -2.0f * screenSize.z * tanHalfVertFoV * aspectRatio;
+                float m20 = (1.0f - 2.0f * lensShift.x) * tanHalfVertFoV * aspectRatio;
+                float m00 = -2.0f * screenSize.z * tanHalfVertFoV * aspectRatio;
 
-            if (renderToCubemap)
-            {
-                // Flip Y.
-                m11 = -m11;
-                m21 = -m21;
-            }
+                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));
+                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));
+            }
 
             // Remove the translation component.
             var homogeneousZero = new Vector4(0, 0, 0, 1);