use another method to load BRDF LUT texture

Prism/src/Prism/Platform/OpenGL/OpenGLTexture.cpp

@@ -18,6 +18,7 @@ namespace Prism
         case TextureFormat::RGB:     return GL_RGB;
         case TextureFormat::RGBA:    return GL_RGBA;
 		case TextureFormat::RGBA16F: return GL_RGBA16F;
+        case TextureFormat::RG8:   return GL_RG8;
         case TextureFormat::RG16F:   return GL_RG16F;
         }
         return 0;
@@ -28,6 +29,7 @@ namespace Prism
     	case TextureFormat::RGB:     return GL_RGB8;
     	case TextureFormat::RGBA:    return GL_RGBA8;
     	case TextureFormat::RGBA16F: return GL_RGBA16F;
+        case TextureFormat::RG8:   return GL_RG8;
     	case TextureFormat::RG16F:   return GL_RG16F;
     	default:                      return 0;
     	}
@@ -38,6 +40,7 @@ namespace Prism
     	case TextureFormat::RGB:     return GL_RGB;
     	case TextureFormat::RGBA:    return GL_RGBA;
     	case TextureFormat::RGBA16F: return GL_RGBA;
+        case TextureFormat::RG8:   return GL_RG;
     	case TextureFormat::RG16F:   return GL_RG;
     	default:                      return 0;
     	}
@@ -137,47 +140,6 @@ namespace Prism
     OpenGLTexture2D::OpenGLTexture2D(const std::string& path, bool srgb, bool isLUT)
         : m_FilePath(path)
     {
-
-    	if (isLUT)
-    	{
-    		int width, height, channels;
-    		float* data = stbi_loadf(path.c_str(), &width, &height, &channels, 2);
-    		if (!data)
-    		{
-    			PM_CORE_ERROR("Failed to load BRDF LUT: {0}", path);
-    			return;
-    		}
-
-    		m_Loaded = true;
-    		m_Width  = width;
-    		m_Height = height;
-    		m_Format = TextureFormat::RG16F;
-    		m_IsHDR  = true;
-    		m_ImageData.Data = (byte*)data;
-
-    		Ref<OpenGLTexture2D> instance = this;
-    		Renderer::Submit([instance, width, height]() mutable
-			{
-				glCreateTextures(GL_TEXTURE_2D, 1, &instance->m_RendererID);
-
-				// 内部格式：双通道 16 位浮点
-				glTextureStorage2D(instance->m_RendererID, 1, GL_RG16F, width, height);
-
-				// 包裹模式必须为 CLAMP_TO_EDGE，防止 LUT 边缘插值错误
-				glTextureParameteri(instance->m_RendererID, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
-				glTextureParameteri(instance->m_RendererID, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
-
-				// LUT 不需要 mipmap，使用线性过滤即可
-				glTextureParameteri(instance->m_RendererID, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-				glTextureParameteri(instance->m_RendererID, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-
-				// 上传数据：紧密排列的 RG 浮点数组
-				glTextureSubImage2D(instance->m_RendererID, 0, 0, 0,
-									width, height, GL_RG, GL_FLOAT, instance->m_ImageData.Data);
-
-				stbi_image_free(instance->m_ImageData.Data);
-			});
-    	}else
     	{
     		int width, height, channels;
     		if (stbi_is_hdr(path.c_str()))
@@ -203,7 +165,7 @@ namespace Prism
     		m_Height = height;
 
     		Ref<OpenGLTexture2D> instance = this;
-    		Renderer::Submit([instance, srgb]() mutable {
+    		Renderer::Submit([instance, srgb, isLUT]() mutable {
 				// TODO: Consolidate properly
 				if (srgb)
 				{
@@ -221,20 +183,32 @@ namespace Prism
 					glGenTextures(1, &instance->m_RendererID);
 					glBindTexture(GL_TEXTURE_2D, instance->m_RendererID);
 
-					glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+
+					if (isLUT)
+					{
+						glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 						glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 
+						glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+						glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+						glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+					}
+					else
+					{
+						glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+						glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 						const GLint wrap = instance->m_Wrap == TextureWrap::Clamp ? GL_CLAMP_TO_EDGE : GL_REPEAT;
-
 						glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrap);
 						glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, wrap);
 						glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, wrap);
+					}
 
 					GLenum internalFormat = PrismToOpenGLTextureFormat(instance->m_Format);
 					GLenum format = srgb ? GL_SRGB8 : (instance->m_IsHDR ? GL_RGB : PrismToOpenGLTextureFormat(instance->m_Format)); // HDR = GL_RGB for now
 					GLenum type = internalFormat == GL_RGBA16F ? GL_FLOAT : GL_UNSIGNED_BYTE;
 					glTexImage2D(GL_TEXTURE_2D, 0, (GLint)internalFormat, (GLint)instance->m_Width, (GLint)instance->m_Height, 0, format, type, instance->m_ImageData.Data);
 
+					if (!isLUT)
 						glGenerateMipmap(GL_TEXTURE_2D);
 
 					glBindTexture(GL_TEXTURE_2D, 0);

Prism/src/Prism/Renderer/Texture.h

@@ -19,7 +19,8 @@ namespace Prism
         RGB = 1,
         RGBA = 2,
         RGBA16F = 3,
-        RG16F = 4,
+        RG8 = 4,
+        RG16F = 5,
     };
 
     enum class TextureWrap