WIP: Render fogs with one draw call per fog instead of re-drawing every surface inside

src.cmake

@@ -108,7 +108,6 @@ set(GLSL_EMBED_LIST
     blur_fp.glsl
     cameraEffects_fp.glsl
     contrast_fp.glsl
-    fogGlobal_fp.glsl
     fxaa_fp.glsl
     fxaa3_11_fp.glsl
     motionblur_fp.glsl
@@ -130,6 +129,8 @@ set(GLSL_EMBED_LIST
     vertexSkinning_vp.glsl
 
     # Regular shaders
+    fogGlobal_vp.glsl
+    fogGlobal_fp.glsl
     fogQuake3_vp.glsl
     fogQuake3_fp.glsl
     generic_vp.glsl

src/engine/renderer/GeometryOptimiser.h

@@ -87,7 +87,6 @@ void MarkShaderBuildScreen( const shaderStage_t* pStage );
 void MarkShaderBuildPortal( const shaderStage_t* pStage );
 void MarkShaderBuildHeatHaze( const shaderStage_t* pStage );
 void MarkShaderBuildLiquid( const shaderStage_t* pStage );
-void MarkShaderBuildFog( const shaderStage_t* pStage );
 
 void MarkShaderBuildIQM( const IQModel_t* model );
 void MarkShaderBuildMDV( const mdvModel_t* model );

src/engine/renderer/Material.cpp

@@ -1114,11 +1114,11 @@ void BindShaderFog( Material* material ) {
 	// since fognum is grouped with the GL state stuff, segregating each fognum in a separate draw call.
 
 	gl_fogQuake3ShaderMaterial->SetUniform_ViewOrigin( backEnd.viewParms.orientation.origin );
-	gl_fogQuake3ShaderMaterial->SetUniform_FogDensity( fog->tcScale );
+	gl_fogQuake3ShaderMaterial->SetUniform_FogDensity( 1.0f / fog->shader->fogParms.depthForOpaque );
 	gl_fogQuake3ShaderMaterial->SetUniform_FogDepthVector( fogDepthVector );
 	gl_fogQuake3ShaderMaterial->SetUniform_FogEyeT( eyeT );
 
-	gl_fogQuake3ShaderMaterial->SetUniform_ColorGlobal_Uint( fog->color );
+	gl_fogQuake3ShaderMaterial->SetUniform_ColorGlobal_Uint( fog->shader->fogParms.color );
 
 	gl_fogQuake3ShaderMaterial->SetUniform_ModelMatrix( backEnd.orientation.transformMatrix );
 	gl_fogQuake3ShaderMaterial->SetUniform_ModelViewProjectionMatrix( glState.modelViewProjectionMatrix[glState.stackIndex] );
@@ -2096,7 +2096,7 @@ void MaterialSystem::RenderMaterial( Material& material, const uint32_t viewID )
 	}
 
 	if( material.shaderBinder == BindShaderFog ) {
-		if ( r_noFog->integer || !r_wolfFog->integer || ( backEnd.refdef.rdflags & RDF_NOWORLDMODEL ) ) {
+		if ( r_noFog->integer || ( backEnd.refdef.rdflags & RDF_NOWORLDMODEL ) ) {
 			return;
 		}
 	}

src/engine/renderer/gl_shader.cpp

@@ -2719,10 +2719,12 @@ GLShader_fogQuake3Material::GLShader_fogQuake3Material() :
 	GLDeformStage( this ) {
 }
 
+// TODO: rename
 GLShader_fogGlobal::GLShader_fogGlobal() :
 	GLShader( "fogGlobal", ATTR_POSITION,
-		false, "screenSpace", "fogGlobal" ),
+		false, "fogGlobal", "fogGlobal" ),
 	u_DepthMap( this ),
+	u_ModelViewProjectionMatrix( this ),
 	u_UnprojectMatrix( this ),
 	u_Color_Float( this ),
 	u_Color_Uint( this ),

src/engine/renderer/gl_shader.h

@@ -3194,6 +3194,7 @@ class GLShader_fogQuake3Material :
 class GLShader_fogGlobal :
 	public GLShader,
 	public u_DepthMap,
+	public u_ModelViewProjectionMatrix,
 	public u_UnprojectMatrix,
 	public u_Color_Float,
 	public u_Color_Uint,

src/engine/renderer/glsl_source/fogGlobal_fp.glsl

@@ -27,6 +27,8 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
 #define DEPTHMAP_GLSL
 
+IN(smooth) vec3 var_Position;
+
 uniform sampler2D	u_DepthMap;
 
 uniform colorPack u_Color;
@@ -37,6 +39,7 @@ uniform mat4		u_UnprojectMatrix;
 
 DECLARE_OUTPUT(vec4)
 
+// This shader can be used to draw a fog volume the viewer is inside of.
 void	main()
 {
 	#insert material_fp
@@ -50,7 +53,9 @@ void	main()
 	P.xyz /= P.w;
 
 	// calculate the length in fog (t is always 1 if eye is in fog)
-	float s = distance(u_ViewOrigin, P.xyz) * u_FogDensity;
+	float depthDist = distance(u_ViewOrigin, P.xyz);
+	float fogBoundaryDist = distance(u_ViewOrigin, var_Position);
+	float s = min(depthDist, fogBoundaryDist) * u_FogDensity;
 
 	vec4 color = vec4(1, 1, 1, GetFogAlpha(s, 1.0));
 

src/engine/renderer/glsl_source/fogGlobal_vp.glsl

@@ -0,0 +1,46 @@
+/*
+===========================================================================
+
+Daemon BSD Source Code
+Copyright (c) 2026 Daemon Developers
+All rights reserved.
+
+This file is part of the Daemon BSD Source Code (Daemon Source Code).
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+	* Redistributions of source code must retain the above copyright
+	  notice, this list of conditions and the following disclaimer.
+	* Redistributions in binary form must reproduce the above copyright
+	  notice, this list of conditions and the following disclaimer in the
+	  documentation and/or other materials provided with the distribution.
+	* Neither the name of the Daemon developers nor the
+	  names of its contributors may be used to endorse or promote products
+	  derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL DAEMON DEVELOPERS BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+===========================================================================
+*/
+
+uniform mat4 u_ModelViewProjectionMatrix;
+
+IN vec3 attr_Position;
+
+OUT(smooth) vec3 var_Position;
+
+void main()
+{
+	vec4 position = vec4(attr_Position, 1.0);
+	gl_Position = u_ModelViewProjectionMatrix * position;
+	var_Position = attr_Position;
+}

src/engine/renderer/tr_backend.cpp

@@ -1423,54 +1423,46 @@ void RB_RenderPostDepthLightTile()
 	GL_CheckErrors();
 }
 
-void RB_RenderGlobalFog()
+// TODO: move with other Render_ functions
+void Render_fogGlobal( shaderStage_t *stage )
 {
-	if ( backEnd.refdef.rdflags & RDF_NOWORLDMODEL )
-	{
-		return;
-	}
-
 	if ( r_noFog->integer )
 	{
 		return;
 	}
 
-	if ( !tr.world || tr.world->globalFog < 0 )
-	{
-		return;
-	}
-
 	GLIMP_LOGCOMMENT( "--- RB_RenderGlobalFog ---" );
 
 	RB_PrepareForSamplingDepthMap();
 
-	GL_Cull( cullType_t::CT_TWO_SIDED );
+	GL_Cull( cullType_t::CT_FRONT_SIDED );
 
 	gl_fogGlobalShader->BindProgram();
 
-	// go back to the world modelview matrix
-	backEnd.orientation = backEnd.viewParms.world;
-
 	{
-		fog_t* fog = &tr.world->fogs[ tr.world->globalFog ];
-
-		GLIMP_LOGCOMMENT( "--- RB_RenderGlobalFog( fogNum = %i ) ---", tr.world->globalFog );
-
 		GL_State( GLS_DEPTHTEST_DISABLE | GLS_SRCBLEND_SRC_ALPHA | GLS_DSTBLEND_ONE_MINUS_SRC_ALPHA );
 
-		gl_fogGlobalShader->SetUniform_FogDensity( fog->tcScale );
+		gl_fogGlobalShader->SetUniform_FogDensity( 1.0f / stage->shader->fogParms.depthForOpaque );
 		gl_fogGlobalShader->SetUniform_ViewOrigin( backEnd.viewParms.orientation.origin );
-		SetUniform_Color( gl_fogGlobalShader, fog->color );
+		SetUniform_Color( gl_fogGlobalShader, stage->shader->fogParms.color );
 	}
 
+	// It's important to avoid far plane clipping
+	matrix_t projection, mvp;
+	MatrixPerspectiveProjectionFovXYInfiniteRH( projection, tr.refdef.fov_x, tr.refdef.fov_y, 1.0f );
+	MatrixMultiply( projection, glState.modelViewMatrix[ glState.stackIndex ], mvp );
+
+	gl_fogGlobalShader->SetUniform_ModelViewProjectionMatrix( mvp );
 	gl_fogGlobalShader->SetUniform_UnprojectMatrix( backEnd.viewParms.unprojectionMatrix );
 
 	// bind u_DepthMap
 	gl_fogGlobalShader->SetUniform_DepthMapBindless(
 		GL_BindToTMU( 1, tr.depthSamplerImage )
 	);
 
-	Tess_InstantScreenSpaceQuad();
+	gl_fogGlobalShader->SetRequiredVertexPointers();
+
+	Tess_DrawElements();
 
 	GL_CheckErrors();
 }
@@ -2801,9 +2793,6 @@ static void RB_RenderView( bool depthPass )
 
 	RB_RenderSSAO();
 
-	// render global fog post process effect
-	RB_RenderGlobalFog();
-
 	TransitionMainToMSAA( GL_COLOR_BUFFER_BIT );
 
 	// draw everything that is translucent

src/engine/renderer/tr_bsp.cpp

@@ -3217,8 +3217,6 @@ static void R_LoadFogs( lump_t *l, lump_t *brushesLump, lump_t *sidesLump )
 	int          count, brushesCount, sidesCount;
 	int          sideNum;
 	int          planeNum;
-	shader_t     *shader;
-	float        d;
 	int          firstSide = 0;
 
 	Log::Debug("...loading fogs" );
@@ -3264,6 +3262,9 @@ static void R_LoadFogs( lump_t *l, lump_t *brushesLump, lump_t *sidesLump )
 
 	sidesCount = sidesLump->filelen / sizeof( *sides );
 
+	std::vector<std::array<float, 3>> fogVerts(8 * count);
+	std::vector<glIndex_t> fogIndexes(6 * 6 * count);
+
 	for ( i = 0; i < count; i++, fogs++ )
 	{
 		out->originalBrushNumber = LittleLong( fogs->brushNum );
@@ -3316,26 +3317,28 @@ static void R_LoadFogs( lump_t *l, lump_t *brushesLump, lump_t *sidesLump )
 			out->bounds[ 1 ][ 2 ] = s_worldData.planes[ planeNum ].dist;
 		}
 
-		// get information from the shader for fog parameters
-		// it says RSF_3D but if there is no shader text found it should probably just error instead
-		// of trying to create an implicit shader from an image...
-		shader = R_FindShader( fogs->shader, RSF_3D );
-
-		out->fogParms = shader->fogParms;
-
-		out->color = Color::Adapt( shader->fogParms.color );
-
-		if ( tr.worldLinearizeTexture )
+		// add faces of fog brush for drawing fog from inside
+		for ( int p = 0; p < 8; p++ )
 		{
-			out->color = out->color.ConvertFromSRGB();
+			fogVerts[ i * 8 + p ][ 0 ] = out->bounds[ p & 1 ][ 0 ];
+			fogVerts[ i * 8 + p ][ 1 ] = out->bounds[ ( p >> 1 ) & 1 ][ 1 ];
+			fogVerts[ i * 8 + p ][ 2 ] = out->bounds[ p >> 2 ][ 2 ];
+		}
+		constexpr int box[ 36 ] = { 2, 3, 0, 0, 3, 1, 0, 1, 4, 4, 1, 5, 2, 0, 6, 6, 0, 4,
+		                            1, 3, 5, 5, 3, 7, 3, 2, 7, 7, 2, 6, 7, 6, 5, 5, 6, 4 };
+		for ( int p = 0; p < 36; p++ )
+		{
+			fogIndexes[ 36 * i + p ] = 8 * i + box[ p ];
 		}
 
-		out->color *= tr.identityLight;
-
-		out->color.SetAlpha( 1 );
+		// add draw surf for fog brush faces
+		out->surf.firstIndex = 36 * i;
+		out->surf.numTriangles = 12;
+		out->surf.surfaceType = surfaceType_t::SF_TRIANGLES;
 
-		d = shader->fogParms.depthForOpaque < 1 ? 1 : shader->fogParms.depthForOpaque;
-		out->tcScale = 1.0f / d;
+		// it says RSF_3D but if there is no shader text found it should probably just error instead
+		// of trying to create an implicit shader from an image...
+		out->shader = R_FindShader( fogs->shader, RSF_3D );
 
 		// ydnar: global fog sets clearcolor/zfar
 		if ( out->originalBrushNumber == -1 )
@@ -3362,6 +3365,20 @@ static void R_LoadFogs( lump_t *l, lump_t *brushesLump, lump_t *sidesLump )
 		out++;
 	}
 
+	vertexAttributeSpec_t attributes[] {
+		{ ATTR_INDEX_POSITION, GL_FLOAT, GL_FLOAT, &fogVerts[ 0 ], 3, sizeof( fogVerts[ 0 ] ), 0 },
+	};
+	VBO_t *fogVBO = R_CreateStaticVBO(
+		"fogs VBO", std::begin( attributes ), std::end( attributes ), fogVerts.size() );
+	IBO_t *fogIBO = R_CreateStaticIBO( "fogs IBO", &fogIndexes[ 0 ], fogIndexes.size() );
+	SetupVAOBuffers( fogVBO, fogIBO, ATTR_POSITION, &fogVBO->VAO );
+
+	for ( int j = 1; j < s_worldData.numFogs; j++ )
+	{
+		s_worldData.fogs[ j ].surf.vbo = fogVBO;
+		s_worldData.fogs[ j ].surf.ibo = fogIBO;
+	}
+
 	Log::Debug("%i fog volumes loaded", s_worldData.numFogs );
 }
 

src/engine/renderer/tr_init.cpp

@@ -222,7 +222,6 @@ Cvar::Cvar<int> r_rendererAPI( "r_rendererAPI", "Renderer API: 0: OpenGL, 1: Vul
 
 	cvar_t      *r_showImages;
 
-	cvar_t      *r_wolfFog;
 	cvar_t      *r_noFog;
 
 	Cvar::Range<Cvar::Cvar<float>> r_forceAmbient( "r_forceAmbient", "Minimal light amount in lightGrid; -1 to use map value",
@@ -1157,7 +1156,6 @@ ScreenshotCmd screenshotPNGRegistration("screenshotPNG", ssFormat_t::SSF_PNG, "p
 		r_heatHaze = Cvar_Get( "r_heatHaze", "1", CVAR_LATCH | CVAR_ARCHIVE );
 		r_noMarksOnTrisurfs = Cvar_Get( "r_noMarksOnTrisurfs", "1", CVAR_CHEAT );
 
-		r_wolfFog = Cvar_Get( "r_wolfFog", "1", CVAR_CHEAT );
 		r_noFog = Cvar_Get( "r_noFog", "0", CVAR_CHEAT );
 
 		Cvar::Latch( r_forceAmbient );
@@ -1543,6 +1541,8 @@ ScreenshotCmd screenshotPNGRegistration("screenshotPNG", ssFormat_t::SSF_PNG, "p
 					gl_fogQuake3Shader->SetDeform( 0 );
 					gl_fogQuake3Shader->MarkProgramForBuilding();
 				}
+
+				gl_fogGlobalShader->MarkProgramForBuilding();
 			}
 
 			for ( int i = 0; i < tr.numModels; i++ ) {