Clarify explanations

vazgriz · vazgriz · commit 3f92f53ada68 · 2018-03-27T23:02:35.000-06:00
diff --git a/09_Generating_Mipmaps.md b/09_Generating_Mipmaps.md
@@ -1,13 +1,13 @@
 ## Introduction
 Our program can now load and render 3D models. In this chapter, we will add one more feature, mipmap generation. Mipmaps are widely used in games and rendering software, and Vulkan gives us complete control over how they are created. 
 
-Mipmaps are precalculated, downscaled versions of an image. Each new image is half the width and height of the previous one.  Mipmaps are used as a form of *Level of Detail.* Objects that are far away from the camera will sample their textures from the smaller mip images. Using smaller images increases the rendering speed and avoids artifacts such as [Moiré patterns](https://en.wikipedia.org/wiki/Moir%C3%A9_pattern). An example of what mipmaps look like:
+Mipmaps are precalculated, downscaled versions of an image. Each new image is half the width and height of the previous one.  Mipmaps are used as a form of *Level of Detail* or *LOD.* Objects that are far away from the camera will sample their textures from the smaller mip images. Using smaller images increases the rendering speed and avoids artifacts such as [Moiré patterns](https://en.wikipedia.org/wiki/Moir%C3%A9_pattern). An example of what mipmaps look like:
 
 ![](/images/mipmaps_example.jpg)
 
 ## Image creation
 
-In Vulkan, each of the mip images is stored in different *mip levels* of a `VkImage`. Mip level 0 is the original image, and each mip level after that is half the size of previous level. The mip levels after level 0 are commonly referred to as the *mip chain.* 
+In Vulkan, each of the mip images is stored in different *mip levels* of a `VkImage`. Mip level 0 is the original image, and the mip levels after level 0 are commonly referred to as the *mip chain.* 
 
 The number of mip levels is specified when the `VkImage` is created. Up until now, we have always set this value to one. We need to calculate the number of mip levels from the dimensions of the image. First, add a class member to store this number:
 
@@ -28,7 +28,7 @@ The value for `mipLevels` can be found once we've loaded the texture in `createT
 
 ```
 
-The `max` function selects the largest dimension. The `log2` function calculates how many times that dimension can be divided by 2. The `floor` function handles cases where the largest dimension is not a power of 2. This value is the number of levels in the mip chain. `1` is added so that the original image has a mip level.
+This calculates the number of levels in the mip chain. The `max` function selects the largest dimension. The `log2` function calculates how many times that dimension can be divided by 2. The `floor` function handles cases where the largest dimension is not a power of 2.  `1` is added so that the original image has a mip level.
 
 To use this value, we need to change the `createImage` and `createImageView` functions to allow us to specify the number of mip levels. Add a `mipLevels` parameter to the functions:
 
@@ -217,7 +217,7 @@ Our texture image's mipmaps are now completely filled.
 
 ## Sampler
 
-While the `VkImage` holds the mipmap data, `VkSampler` controls how that data is read while rendering. Vulkan allows us to specify `minLod`, `maxLod`, `mipLodBias`, and `mipmapMode`. When a texture is sampled, the sampler selects a mip level according to the following pseudocode:
+While the `VkImage` holds the mipmap data, `VkSampler` controls how that data is read while rendering. Vulkan allows us to specify `minLod`, `maxLod`, `mipLodBias`, and `mipmapMode` ("Lod" means "Level of Detail"). When a texture is sampled, the sampler selects a mip level according to the following pseudocode:
 
 ```c++
     lod = getLodLevelFromScreenSize(); //smaller when the object is close, may be negative
@@ -244,7 +244,7 @@ The sample operation is also affected by `lod`:
     }
 ```
 
-If the object is close to the camera, `magFilter` is used as the filter. If the object is further from the camera, `minFilter` is used. Normally, `lod` is non-negative, and is only 0 when close the camera. `mipLodBias` lets us force Vulkan to use lower mip levels than it normally would.
+If the object is close to the camera, `magFilter` is used as the filter. If the object is further from the camera, `minFilter` is used. Normally, `lod` is non-negative, and is only 0 when close the camera. `mipLodBias` lets us force Vulkan to use lower `lod` and `level` than it would normally use.
 
 To see the results of this chapter, we need to choose values for our `textureSampler`. We've already set the `minFilter` and `magFilter` to use `VK_FILTER_LINEAR`. We just need to choose values for `minLod`, `maxLod`, `mipLodBias`, and `mipmapMode`.
 
