From 6c77608c345cfdbb8a456e1ff0360f53f5913d90 Mon Sep 17 00:00:00 2001
From: mittorn <mittorn@disroot.org>
Date: Wed, 21 Feb 2024 21:07:54 +0300
Subject: [PATCH] ref_gl: implement color-modulate overbrigths with gl_vbo
 using texture GL_COMBINE

---
 ref/gl/gl_local.h  |  1 +
 ref/gl/gl_opengl.c |  2 ++
 ref/gl/gl_rmain.c  |  3 ++-
 ref/gl/gl_rsurf.c  | 23 +++++++++++++++++++----
 4 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/ref/gl/gl_local.h b/ref/gl/gl_local.h
index 627ea8c7..e276c322 100644
--- a/ref/gl/gl_local.h
+++ b/ref/gl/gl_local.h
@@ -780,6 +780,7 @@ extern convar_t	r_traceglow;
 extern convar_t	r_vbo;
 extern convar_t	r_vbo_dlightmode;
 extern convar_t	r_vbo_detail;
+extern convar_t	r_vbo_overbrightmode;
 extern convar_t r_studio_sort_textures;
 extern convar_t r_studio_drawelements;
 extern convar_t r_ripple;
diff --git a/ref/gl/gl_opengl.c b/ref/gl/gl_opengl.c
index 694adfe4..7e4a18fa 100644
--- a/ref/gl/gl_opengl.c
+++ b/ref/gl/gl_opengl.c
@@ -32,6 +32,7 @@ CVAR_DEFINE_AUTO( gl_round_down, "2", FCVAR_GLCONFIG|FCVAR_READ_ONLY, "round tex
 CVAR_DEFINE( r_vbo, "gl_vbo", "0", FCVAR_ARCHIVE, "draw world using VBO (known to be glitchy)" );
 CVAR_DEFINE( r_vbo_detail, "gl_vbo_detail", "0", FCVAR_ARCHIVE, "detail vbo mode (0: disable, 1: multipass, 2: singlepass, broken decal dlights)" );
 CVAR_DEFINE( r_vbo_dlightmode, "gl_vbo_dlightmode", "1", FCVAR_ARCHIVE, "vbo dlight rendering mode (0-1)" );
+CVAR_DEFINE( r_vbo_overbrightmode, "gl_vbo_overbrightmode", "0", FCVAR_ARCHIVE, "vbo overbright rendering mode (0-1)" );
 CVAR_DEFINE_AUTO( r_ripple, "0", FCVAR_GLCONFIG, "enable software-like water texture ripple simulation" );
 CVAR_DEFINE_AUTO( r_ripple_updatetime, "0.05", FCVAR_GLCONFIG, "how fast ripple simulation is" );
 CVAR_DEFINE_AUTO( r_ripple_spawntime, "0.1", FCVAR_GLCONFIG, "how fast new ripples spawn" );
@@ -1248,6 +1249,7 @@ static void R_CheckVBO( void )
 
 	gEngfuncs.Cvar_RegisterVariable( &r_vbo );
 	gEngfuncs.Cvar_RegisterVariable( &r_vbo_dlightmode );
+	gEngfuncs.Cvar_RegisterVariable( &r_vbo_overbrightmode );
 	gEngfuncs.Cvar_RegisterVariable( &r_vbo_detail );
 }
 
diff --git a/ref/gl/gl_rmain.c b/ref/gl/gl_rmain.c
index 94d31ed3..62850504 100644
--- a/ref/gl/gl_rmain.c
+++ b/ref/gl/gl_rmain.c
@@ -1011,10 +1011,11 @@ static void R_CheckGamma( void )
 		ClearBits( gl_overbright.flags, FCVAR_CHANGED );
 	}
 
-	if( gl_overbright.value && FBitSet( r_vbo.flags, FCVAR_CHANGED ))
+	if( gl_overbright.value && ( FBitSet( r_vbo.flags, FCVAR_CHANGED ) || FBitSet( r_vbo_overbrightmode.flags, FCVAR_CHANGED ) ) )
 	{
 		rebuild = true;
 		ClearBits( r_vbo.flags, FCVAR_CHANGED );
+		ClearBits( r_vbo_overbrightmode.flags, FCVAR_CHANGED );
 	}
 
 	if( rebuild )
diff --git a/ref/gl/gl_rsurf.c b/ref/gl/gl_rsurf.c
index 113f47b4..493cd63d 100644
--- a/ref/gl/gl_rsurf.c
+++ b/ref/gl/gl_rsurf.c
@@ -718,7 +718,7 @@ static void R_BuildLightMap( msurface_t *surf, byte *dest, int stride, qboolean
 	tmax = ( info->lightextents[1] / sample_size ) + 1;
 	size = smax * tmax;
 	if( gl_overbright.value )
-		lightscale = r_vbo.value ? 171 : 256;
+		lightscale = (r_vbo.value && !r_vbo_overbrightmode.value) ? 171 : 256;
 	else lightscale = ( pow( 2.0f, 1.0f / v_lightgamma->value ) * 256 ) + 0.5;
 
 	lm = surf->samples;
@@ -2189,15 +2189,30 @@ static void R_SetLightmap( void )
 
 	if( gl_overbright.value )
 	{
-		// GLfloat color[4] = { 128.0f / 192.0f, 128.0f / 192.0f, 128.0f / 192.0f, 1.0f };
+		if( r_vbo_overbrightmode.value == 1 )
+		{
+			GLfloat color[4] = { 128.0f / 192.0f, 128.0f / 192.0f, 128.0f / 192.0f, 1.0f };
+			int tmu = glState.activeTMU;
+			GL_SelectTexture( tmu - 1 );
+			pglTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
+			pglTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_MODULATE );
+			pglTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_CONSTANT_ARB );
+			pglTexEnvi( GL_TEXTURE_ENV, GL_OPERAND0_RGB_ARB, GL_SRC_COLOR );
+			pglTexEnvi( GL_TEXTURE_ENV, GL_OPERAND1_RGB_ARB, GL_SRC_COLOR );
+			pglTexEnvi( GL_TEXTURE_ENV, GL_OPERAND2_RGB_ARB, GL_SRC_COLOR );
+			pglTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_TEXTURE );
+			// doesn't work here for some reason
+			pglTexEnvfv( GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, color );
+			GL_SelectTexture( tmu );
+		}
 
 		pglTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
 		pglTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_MODULATE );
 		pglTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_PREVIOUS_ARB );
 		pglTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_TEXTURE );
+		pglTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_ALPHA_ARB, GL_REPLACE );
+		pglTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_ALPHA_ARB, GL_PREVIOUS_ARB );
 		pglTexEnvi( GL_TEXTURE_ENV, GL_RGB_SCALE_ARB, 2 );
-		// doesn't work here for some reason
-		// pglTexEnvfv( GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, color );
 	}
 	else
 	{