From d998aaad12511751a70bbc05d410104d274b104d Mon Sep 17 00:00:00 2001
From: Philip Rebohle <philip.rebohle@tu-dortmund.de>
Date: Wed, 16 Oct 2019 18:18:13 +0200
Subject: [PATCH] [dxvk] Add some component mapping helpers

---
 src/dxvk/dxvk_util.cpp | 53 ++++++++++++++++++++++++++++++++++++++++++
 src/dxvk/dxvk_util.h   | 16 +++++++++++++
 2 files changed, 69 insertions(+)

diff --git a/src/dxvk/dxvk_util.cpp b/src/dxvk/dxvk_util.cpp
index bde6df40..6fc47e29 100644
--- a/src/dxvk/dxvk_util.cpp
+++ b/src/dxvk/dxvk_util.cpp
@@ -140,6 +140,59 @@ namespace dxvk::util {
   }
 
 
+  static VkComponentMapping normalizeComponentMapping(
+          VkComponentMapping          mapping) {
+    mapping.r = mapping.r == VK_COMPONENT_SWIZZLE_IDENTITY ? VK_COMPONENT_SWIZZLE_R : mapping.r;
+    mapping.g = mapping.g == VK_COMPONENT_SWIZZLE_IDENTITY ? VK_COMPONENT_SWIZZLE_G : mapping.g;
+    mapping.b = mapping.b == VK_COMPONENT_SWIZZLE_IDENTITY ? VK_COMPONENT_SWIZZLE_B : mapping.b;
+    mapping.a = mapping.a == VK_COMPONENT_SWIZZLE_IDENTITY ? VK_COMPONENT_SWIZZLE_A : mapping.a;
+    return mapping;
+  }
+
+
+  static VkComponentSwizzle resolveComponentSwizzle(
+          VkComponentSwizzle          swizzle,
+          VkComponentMapping          dstMapping,
+          VkComponentMapping          srcMapping) {
+    VkComponentSwizzle dstSwizzle = VK_COMPONENT_SWIZZLE_IDENTITY;
+    if (dstMapping.r == swizzle) dstSwizzle = VK_COMPONENT_SWIZZLE_R;
+    if (dstMapping.g == swizzle) dstSwizzle = VK_COMPONENT_SWIZZLE_G;
+    if (dstMapping.b == swizzle) dstSwizzle = VK_COMPONENT_SWIZZLE_B;
+    if (dstMapping.a == swizzle) dstSwizzle = VK_COMPONENT_SWIZZLE_A;
+    
+    switch (dstSwizzle) {
+      case VK_COMPONENT_SWIZZLE_R: return srcMapping.r;
+      case VK_COMPONENT_SWIZZLE_G: return srcMapping.g;
+      case VK_COMPONENT_SWIZZLE_B: return srcMapping.b;
+      case VK_COMPONENT_SWIZZLE_A: return srcMapping.a;
+      default: return VK_COMPONENT_SWIZZLE_IDENTITY;
+    }
+  }
+
+
+  VkComponentMapping resolveSrcComponentMapping(
+          VkComponentMapping          dstMapping,
+          VkComponentMapping          srcMapping) {
+    dstMapping = normalizeComponentMapping(dstMapping);
+
+    VkComponentMapping result;
+    result.r = resolveComponentSwizzle(VK_COMPONENT_SWIZZLE_R, dstMapping, srcMapping);
+    result.g = resolveComponentSwizzle(VK_COMPONENT_SWIZZLE_G, dstMapping, srcMapping);
+    result.b = resolveComponentSwizzle(VK_COMPONENT_SWIZZLE_B, dstMapping, srcMapping);
+    result.a = resolveComponentSwizzle(VK_COMPONENT_SWIZZLE_A, dstMapping, srcMapping);
+    return result;
+  }
+
+
+  bool isIdentityMapping(
+          VkComponentMapping          mapping) {
+    return (mapping.r == VK_COMPONENT_SWIZZLE_R || mapping.r == VK_COMPONENT_SWIZZLE_IDENTITY)
+        && (mapping.g == VK_COMPONENT_SWIZZLE_G || mapping.g == VK_COMPONENT_SWIZZLE_IDENTITY)
+        && (mapping.b == VK_COMPONENT_SWIZZLE_B || mapping.b == VK_COMPONENT_SWIZZLE_IDENTITY)
+        && (mapping.a == VK_COMPONENT_SWIZZLE_A || mapping.a == VK_COMPONENT_SWIZZLE_IDENTITY);
+  }
+
+
   uint32_t getComponentIndex(
           VkComponentSwizzle          component,
           uint32_t                    identity) {
diff --git a/src/dxvk/dxvk_util.h b/src/dxvk/dxvk_util.h
index 86d8b79c..06715570 100644
--- a/src/dxvk/dxvk_util.h
+++ b/src/dxvk/dxvk_util.h
@@ -225,7 +225,23 @@ namespace dxvk::util {
    */
   VkComponentMapping invertComponentMapping(
           VkComponentMapping          mapping);
+
+  /**
+   * \brief Resolves source component mapping
+   *
+   * Returns the source component mapping after rearranging
+   * the destination mapping to be the identity mapping.
+   * \param [in] dstMapping Destination mapping
+   * \param [in] srcMapping Source mapping
+   * \returns Adjusted src component mapping
+   */
+  VkComponentMapping resolveSrcComponentMapping(
+          VkComponentMapping          dstMapping,
+          VkComponentMapping          srcMapping);
   
+  bool isIdentityMapping(
+          VkComponentMapping          mapping);
+
   /**
    * \brief Computes component index for a component swizzle
    *