Remove support for 3-channel images.

These are not well-supported by Vulkan implementations and not used very
often.

Fixes a lot of validation errors.

Signed-off-by: Robert Quill <robert.quill@imgtec.com>

src/Image.cpp

@@ -26,9 +26,9 @@ Image::init(void* data,
           "Kompute Image data is smaller than the requested image size");
     }
 
-    if (numChannels > 4) {
+    if (numChannels > 4 || numChannels == 3) {
         throw std::runtime_error(
-          "Kompute Images can only have up to 4 channels");
+          "Kompute Images can only have up to 1, 2 or 4 channels");
     }
 
     if (tiling == vk::ImageTiling::eOptimal &&

test/TestImage.cpp

@@ -45,6 +45,14 @@ TEST(TestImage, DataTypes)
     const int height = 3;
 
     for (int numChannels = 1; numChannels <= 4; numChannels++) {
+
+      // 3-channel images are not supported and should throw an exception.
+      // This is tested by a different test.
+      if (numChannels == 3)
+      {
+        continue;
+      }
+
         {
             std::vector<float> vec(width * height * numChannels);
             std::shared_ptr<kp::ImageT<float>> image =
@@ -130,7 +138,8 @@ TEST(TestImage, InvalidNumberOfChannels)
     // channels.
     std::vector<float> vec(3 * 3 * 5);
 
-    // There should be between 1 and 4 channels.
+    // There should be 1,2 or 4 channels.
     EXPECT_THROW(mgr.image(vec, 3, 3, 0), std::runtime_error);
+    EXPECT_THROW(mgr.image(vec, 3, 3, 3), std::runtime_error);
     EXPECT_THROW(mgr.image(vec, 3, 3, 5), std::runtime_error);
 }