From b4eb9c59725dd5e8ab82cf560480a26644dc589d Mon Sep 17 00:00:00 2001
From: sindra <sindra@roblox.com>
Date: Tue, 28 Jul 2020 10:07:16 -0700
Subject: [PATCH] Added some support for uncompressed texture for ktx

---
 src/nvtt/Context.cpp | 112 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 107 insertions(+), 5 deletions(-)

diff --git a/src/nvtt/Context.cpp b/src/nvtt/Context.cpp
index 354ffef..8255de2 100644
--- a/src/nvtt/Context.cpp
+++ b/src/nvtt/Context.cpp
@@ -540,6 +540,67 @@ void Compressor::Private::quantize(Surface & img, const CompressionOptions::Priv
     }
 }
 
+namespace
+{
+	enum
+	{
+		// internal format
+		GL_RGB8 = 0x8051,
+		GL_RGBA8 = 0x8058,
+		GL_R16 = 0x822A,
+		GL_RGBA16F = 0x881A,
+		GL_R11F_G11F_B10F = 0x8C3A,
+
+		// type
+		GL_UNSIGNED_BYTE = 0x1401,
+		GL_HALF_FLOAT = 0x140B,
+		GL_UNSIGNED_INT_10F_11F_11F_REV = 0x8C3B,
+		GL_UNSIGNED_SHORT = 0x1403,
+
+		// format
+		GL_RED = 0x1903,
+		GL_RGB = 0x1907,
+		GL_RGBA = 0x1908,
+		GL_BGR = 0x80E0,
+		GL_BGRA = 0x80E1,
+	};
+
+	struct GLFormatDescriptor
+	{
+		uint glFormat; // for uncompressed texture glBaseInternalFormat == glFormat
+		uint glInternalFormat;
+		uint glType;
+		uint glTypeSize;
+		RGBAPixelFormat pixelFormat;
+	};
+
+	static const GLFormatDescriptor s_glFormats[] =
+	{
+		{ GL_BGR,  GL_RGB8,  GL_UNSIGNED_BYTE, 1, { 24, 0xFF0000,   0xFF00,     0xFF,       0 } },
+		{ GL_BGRA, GL_RGBA8, GL_UNSIGNED_BYTE, 1, { 32, 0xFF0000,   0xFF00,     0xFF,       0xFF000000 } },
+		{ GL_RGBA, GL_RGBA8, GL_UNSIGNED_BYTE, 1, { 32, 0xFF,       0xFF00,     0xFF0000,   0xFF000000 } },
+	};
+
+	static const uint s_glFormatCount = NV_ARRAY_SIZE(s_glFormats);
+
+	static const GLFormatDescriptor* findGLFormat(uint bitcount, uint rmask, uint gmask, uint bmask, uint amask)
+	{
+		for (int i = 0; i < s_glFormatCount; i++)
+		{
+			if (s_glFormats[i].pixelFormat.bitcount == bitcount &&
+				s_glFormats[i].pixelFormat.rmask == rmask &&
+				s_glFormats[i].pixelFormat.gmask == gmask &&
+				s_glFormats[i].pixelFormat.bmask == bmask &&
+				s_glFormats[i].pixelFormat.amask == amask)
+			{
+				return &s_glFormats[i];
+			}
+		}
+
+		return nullptr;
+	}
+}
+
 bool Compressor::Private::outputHeader(nvtt::TextureType textureType, int w, int h, int d, int arraySize, int mipmapCount, bool isNormalMap, const CompressionOptions::Private & compressionOptions, const OutputOptions::Private & outputOptions) const
 {
     if (w <= 0 || h <= 0 || d <= 0 || arraySize <= 0 || mipmapCount <= 0)
@@ -840,13 +901,54 @@ bool Compressor::Private::outputHeader(nvtt::TextureType textureType, int w, int
 
         bool supported = true;
 
-        // TODO non-compressed formats
         if (compressionOptions.format == Format_RGBA)
         {
-            //header.glType = ?;
-            //header.glTypeSize = ?;
-            //header.glFormat = ?;
-        }
+			const uint bitcount = compressionOptions.getBitCount();
+
+			if (compressionOptions.pixelType == PixelType_Float) {
+				if (compressionOptions.rsize == 16 && compressionOptions.gsize == 16 && compressionOptions.bsize == 16 && compressionOptions.asize == 16) {
+					header.glType = GL_HALF_FLOAT;
+					header.glTypeSize = 2;
+					header.glFormat = GL_RGBA;
+					header.glInternalFormat = GL_RGBA16F;
+					header.glBaseInternalFormat = GL_RGBA;
+
+				}
+				else if (compressionOptions.rsize == 11 && compressionOptions.gsize == 11 && compressionOptions.bsize == 10 && compressionOptions.asize == 0) {
+					header.glType = GL_UNSIGNED_INT_10F_11F_11F_REV;
+					header.glTypeSize = 4;
+					header.glFormat = GL_RGB;
+					header.glInternalFormat = GL_R11F_G11F_B10F;
+					header.glBaseInternalFormat = GL_RGB;
+				}
+				else {
+					supported = false;
+				}
+			}
+			else {
+				if (bitcount == 16 && compressionOptions.rsize == 16) {
+					header.glType = GL_UNSIGNED_SHORT;
+					header.glTypeSize = 2;
+					header.glFormat = GL_RED;
+					header.glInternalFormat = GL_R16;
+					header.glBaseInternalFormat = GL_RED;
+				}
+				else {
+					const GLFormatDescriptor* glFormatDesc = findGLFormat(compressionOptions.bitcount, compressionOptions.rmask, compressionOptions.gmask, compressionOptions.bmask, compressionOptions.amask);
+
+					if (glFormatDesc) {
+						header.glType = glFormatDesc->glType;
+						header.glTypeSize = glFormatDesc->glTypeSize;
+						header.glFormat = glFormatDesc->glFormat;
+						header.glInternalFormat = glFormatDesc->glInternalFormat;
+						header.glBaseInternalFormat = header.glFormat;
+					}
+					else {
+						supported = false;
+					}
+				}
+			}
+		}
         else
         {
             header.glType = 0;