Amend the ambient fog logic to be disabled if fog density/start is set to zero. This fixes a regression where the sky stops drawing in lost world.

Rewrite the scroll fog shader slightly. Scroll fog is a 2d layer, it has no depth, or can be considered to be drawn at infinity, therefore is not effected by the viewport light. The scroll attenatuion value also I think attenatutes the scroll fog alpha value. This fixes various effects in emergency call ambulance.

Src/Graphics/New3D/New3D.cpp

@@ -207,7 +207,7 @@ void CNew3D::DrawScrollFog()
 					rgba[2] = vp.fogParams[2];
 					rgba[3] = vp.scrollFog;
 					glViewport(vp.x, vp.y, vp.width, vp.height);
-					m_r3dScrollFog.DrawScrollFog(rgba, vp.scrollAtt, vp.fogParams[6], vp.spotFogColor, vp.spotEllipse);
+					m_r3dScrollFog.DrawScrollFog(rgba, vp.scrollAtt, vp.fogParams[6]);
 				}
 			}
 		}
@@ -223,22 +223,29 @@ void CNew3D::DrawAmbientFog()
 	// Does this work with scroll fog? Well technically scroll fog already takes into account the fog ambient as it darkens the fog colour
 
 	// Let's pick the lowest fog ambient value
+	// Check for fog density or a fog start value, otherwise the effect seems to be disabled (lost world)
 
 	float fogAmbient = 1.0f;
 	Node* nodePtr = nullptr;
 
 	for (auto& n : m_nodes) {
+
+		// check to see if we have a fog density or fog start
+		if (n.viewport.fogParams[3] <= 0.0f && n.viewport.fogParams[4] <= 0.0f) {
+			continue;
+		}
+
 		if (n.viewport.fogParams[6] < fogAmbient) {
 			nodePtr = &n;
 			fogAmbient = n.viewport.fogParams[6];
 		}
 	}
 
-	if (fogAmbient < 1.0f) {
+	if (nodePtr) {
 		auto& vp = nodePtr->viewport;
 		float rgba[] = { 0.0f, 0.0f, 0.0f, 1.0f - fogAmbient };
 		glViewport(vp.x, vp.y, vp.width, vp.height);
-		m_r3dScrollFog.DrawScrollFog(rgba, vp.scrollAtt, vp.fogParams[6], vp.spotFogColor, vp.spotEllipse);
+		m_r3dScrollFog.DrawScrollFog(rgba, 0.0f, 1.0f);
 	}
 }
 

Src/Graphics/New3D/R3DScrollFog.cpp

@@ -26,18 +26,6 @@ static const char *fragmentShaderFog = R"glsl(
 uniform float	fogAttenuation;
 uniform float	fogAmbient;
 uniform vec4	fogColour;
-uniform vec3	spotFogColor;
-uniform vec4	spotEllipse;
-
-// Spotlight on fog
-float	ellipse;
-vec2	position, size;
-vec3	lSpotFogColor;
-
-// Scroll fog
-float	lfogAttenuation;
-vec3	lFogColor;
-vec4	scrollFog;
 
 // outputs
 layout(location = 0) out vec4 out0;		// opaque
@@ -56,21 +44,10 @@ void WriteOutputs(vec4 colour)
 void main()
 {
 	// Scroll fog base color
-	lFogColor = fogColour.rgb * fogAmbient;
-
-	// Spotlight on fog (area) 
-	position = spotEllipse.xy;
-	size = spotEllipse.zw;
-	ellipse = length((gl_FragCoord.xy - position) / size);
-	ellipse = ellipse * ellipse;			// decay rate = square of distance from center
-	ellipse = 1.0 - ellipse;				// invert
-	ellipse = max(0.0, ellipse);			// clamp
-
-	// Spotlight on fog (color)
-	lSpotFogColor = mix(spotFogColor * ellipse * fogColour.rgb, vec3(0.0), fogAttenuation);
+	vec3 lFogColor = fogColour.rgb * fogAmbient;
 
 	// Scroll fog density
-	scrollFog = vec4(lFogColor + lSpotFogColor, fogColour.a);
+	vec4 scrollFog = vec4(lFogColor, fogColour.a * (1.0 - fogAttenuation));
 
 	// Final Color
 	WriteOutputs(scrollFog);
@@ -105,7 +82,7 @@ R3DScrollFog::~R3DScrollFog()
 	}
 }
 
-void R3DScrollFog::DrawScrollFog(float rgba[4], float attenuation, float ambient, float *spotRGB, float *spotEllipse)
+void R3DScrollFog::DrawScrollFog(float rgba[4], float attenuation, float ambient)
 {
 	// some ogl states
 	glDepthMask			(GL_FALSE);			// disable z writes
@@ -116,8 +93,6 @@ void R3DScrollFog::DrawScrollFog(float rgba[4], float attenuation, float ambient
 	glUniform4fv		(m_locFogColour, 1, rgba);
 	glUniform1f			(m_locFogAttenuation, attenuation);
 	glUniform1f			(m_locFogAmbient, ambient);
-	glUniform3fv		(m_locSpotFogColor, 1, spotRGB);
-	glUniform4fv		(m_locSpotEllipse, 1, spotEllipse);
 
 	glDrawArrays		(GL_TRIANGLE_STRIP, 0, 4);
 
@@ -135,8 +110,6 @@ void R3DScrollFog::AllocResources()
 	m_locFogColour		= glGetUniformLocation(m_shaderProgram, "fogColour");
 	m_locFogAttenuation	= glGetUniformLocation(m_shaderProgram, "fogAttenuation");
 	m_locFogAmbient		= glGetUniformLocation(m_shaderProgram, "fogAmbient");
-	m_locSpotFogColor	= glGetUniformLocation(m_shaderProgram, "spotFogColor");
-	m_locSpotEllipse	= glGetUniformLocation(m_shaderProgram, "spotEllipse");
 }
 
 void R3DScrollFog::DeallocResources()

Src/Graphics/New3D/R3DScrollFog.h

@@ -13,7 +13,7 @@ public:
 	R3DScrollFog(const Util::Config::Node &config);
 	~R3DScrollFog();
 
-	void DrawScrollFog(float rbga[4], float attenuation, float ambient, float *spotRGB, float *spotEllipse);
+	void DrawScrollFog(float rbga[4], float attenuation, float ambient);
 
 private:
 
@@ -29,8 +29,6 @@ private:
 	GLint m_locFogColour;
 	GLint m_locFogAttenuation;
 	GLint m_locFogAmbient;
-	GLint m_locSpotFogColor;
-	GLint m_locSpotEllipse;
 
 	GLuint m_vao;
 };