From 7ff1d5877d0eb355dbb457758f82d8388179b038 Mon Sep 17 00:00:00 2001
From: Alug <alufoliehorst@gmail.com>
Date: Thu, 1 Feb 2024 18:16:24 +0100
Subject: [PATCH] Replace glBuild2DMipmaps with GL_GENERATE_MIPMAPS

Quote "gluBuild2DMipmaps. Never use this."
gluBuild2DMipmaps was causing massive stutters on many maps on windows
this replaces it with GL_GENERATE_MIPMAP and removes glBuild2DMipmaps completely

https://www.khronos.org/opengl/wiki/Common_Mistakes
---
 src/hardware/r_opengl/r_opengl.c | 18 ++++++++----------
 src/hardware/r_opengl/r_opengl.h |  1 +
 src/sdl/ogl_sdl.c                |  5 +++++
 3 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/src/hardware/r_opengl/r_opengl.c b/src/hardware/r_opengl/r_opengl.c
index ea831e41d..932cfbaff 100644
--- a/src/hardware/r_opengl/r_opengl.c
+++ b/src/hardware/r_opengl/r_opengl.c
@@ -77,6 +77,7 @@ static GLint min_filter = GL_LINEAR;
 static GLint mag_filter = GL_LINEAR;
 static GLint anisotropic_filter = 0;
 static boolean model_lighting = false;
+boolean supportMipMap = false;
 
 const GLubyte *gl_version = NULL;
 const GLubyte *gl_renderer = NULL;
@@ -397,9 +398,6 @@ static PFNglCopyTexImage2D pglCopyTexImage2D;
 typedef void (APIENTRY * PFNglCopyTexSubImage2D) (GLenum target, GLint level, GLint xoffset, GLint yoffset, GLint x, GLint y, GLsizei width, GLsizei height);
 static PFNglCopyTexSubImage2D pglCopyTexSubImage2D;
 #endif
-/* GLU functions */
-typedef GLint (APIENTRY * PFNgluBuild2DMipmaps) (GLenum target, GLint internalFormat, GLsizei width, GLsizei height, GLenum format, GLenum type, const void *data);
-static PFNgluBuild2DMipmaps pgluBuild2DMipmaps;
 
 /* 1.3 functions for multitexturing */
 typedef void (APIENTRY *PFNglActiveTexture) (GLenum);
@@ -907,9 +905,6 @@ void SetupGLFunc4(void)
 	pglUniform3fv = GetGLFunc("glUniform3fv");
 	pglGetUniformLocation = GetGLFunc("glGetUniformLocation");
 #endif
-
-	// GLU
-	pgluBuild2DMipmaps = GetGLFunc("gluBuild2DMipmaps");
 }
 
 EXPORT boolean HWRAPI(CompileShaders) (void)
@@ -1887,7 +1882,8 @@ EXPORT void HWRAPI(UpdateTexture) (GLMipmap_t *pTexInfo)
 		//pglTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, ptex);
 		if (MipMap)
 		{
-			pgluBuild2DMipmaps(GL_TEXTURE_2D, GL_LUMINANCE_ALPHA, w, h, GL_RGBA, GL_UNSIGNED_BYTE, ptex);
+			pglTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
+			pglTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE_ALPHA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, ptex);
 			pglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_LOD, 0);
 			if (pTexInfo->flags & TF_TRANSPARENT)
 				pglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LOD, 0); // No mippmaps on transparent stuff
@@ -1908,7 +1904,8 @@ EXPORT void HWRAPI(UpdateTexture) (GLMipmap_t *pTexInfo)
 		//pglTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, ptex);
 		if (MipMap)
 		{
-			pgluBuild2DMipmaps(GL_TEXTURE_2D, GL_ALPHA, w, h, GL_RGBA, GL_UNSIGNED_BYTE, ptex);
+			pglTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
+			pglTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, ptex);
 			pglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_LOD, 0);
 			if (pTexInfo->flags & TF_TRANSPARENT)
 				pglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LOD, 0); // No mippmaps on transparent stuff
@@ -1928,7 +1925,8 @@ EXPORT void HWRAPI(UpdateTexture) (GLMipmap_t *pTexInfo)
 	{
 		if (MipMap)
 		{
-			pgluBuild2DMipmaps(GL_TEXTURE_2D, textureformatGL, w, h, GL_RGBA, GL_UNSIGNED_BYTE, ptex);
+			pglTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
+			pglTexImage2D(GL_TEXTURE_2D, 0, textureformatGL, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, ptex);
 			// Control the mipmap level of detail
 			pglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_LOD, 0); // the lower the number, the higer the detail
 			if (pTexInfo->flags & TF_TRANSPARENT)
@@ -2463,7 +2461,7 @@ EXPORT void HWRAPI(SetSpecialState) (hwdspecialstate_t IdState, INT32 Value)
 					mag_filter = GL_LINEAR;
 					min_filter = GL_NEAREST;
 			}
-			if (!pgluBuild2DMipmaps)
+			if (!supportMipMap)
 			{
 				MipMap = GL_FALSE;
 				min_filter = GL_LINEAR;
diff --git a/src/hardware/r_opengl/r_opengl.h b/src/hardware/r_opengl/r_opengl.h
index f44e0818b..8e4784c65 100644
--- a/src/hardware/r_opengl/r_opengl.h
+++ b/src/hardware/r_opengl/r_opengl.h
@@ -126,6 +126,7 @@ extern GLint			screen_width;
 extern GLint			screen_height;
 extern GLbyte			screen_depth;
 extern GLint			maximumAnisotropy;
+extern boolean 			supportMipMap;
 
 /**	\brief OpenGL flags for video driver
 */
diff --git a/src/sdl/ogl_sdl.c b/src/sdl/ogl_sdl.c
index db0538195..81b1314e0 100644
--- a/src/sdl/ogl_sdl.c
+++ b/src/sdl/ogl_sdl.c
@@ -189,6 +189,11 @@ boolean OglSdlSurface(INT32 w, INT32 h)
 	else
 		maximumAnisotropy = 1;
 
+	if (atof((const char*)gl_version) >= 1.4)
+		supportMipMap = true;
+	else
+		supportMipMap = false;
+
 	SetupGLFunc4();
 
 	glanisotropicmode_cons_t[1].value = maximumAnisotropy;