fix missing cloud fog

client/shaders/cloud_shader/opengl_fragment.glsl

@@ -1,6 +1,17 @@
+uniform vec4 fogColor;
+uniform float fogDistance;
+uniform float fogShadingParameter;
+varying vec3 eyeVec;
+
 varying lowp vec4 varColor;
 
 void main(void)
 {
-	gl_FragColor = varColor;
+	vec4 col = varColor;
+
+	float clarity = clamp(fogShadingParameter
+		- fogShadingParameter * length(eyeVec) / fogDistance, 0.0, 1.0);
+	col.rgb = mix(fogColor.rgb, col.rgb, clarity);
+
+	gl_FragColor = col;
 }

client/shaders/cloud_shader/opengl_vertex.glsl

@@ -2,6 +2,8 @@ uniform vec4 emissiveColor;
 
 varying lowp vec4 varColor;
 
+varying vec3 eyeVec;
+
 void main(void)
 {
 	gl_Position = mWorldViewProj * inVertexPosition;
@@ -13,6 +15,7 @@ void main(void)
 #endif
 
 	color *= emissiveColor;
-
 	varColor = color;
+
+	eyeVec = -(mWorldView * inVertexPosition).xyz;
 }

src/client/clouds.cpp

@@ -108,7 +108,6 @@ void Clouds::updateMesh()
 	);
 
 	// Only update mesh if it has moved enough, this saves lots of GPU buffer uploads.
-	// In practice the fog hides the delay in updating.
 	constexpr float max_d = 5 * BS;
 
 	if (!m_mesh_valid) {

src/gui/guiEngine.cpp

@@ -341,6 +341,9 @@ GUIEngine::~GUIEngine()
 /******************************************************************************/
 void GUIEngine::cloudInit()
 {
+	m_shader_source->addShaderConstantSetterFactory(
+		new FogShaderConstantSetterFactory());
+
 	m_cloud.clouds = make_irr<Clouds>(m_smgr, m_shader_source.get(), -1, rand());
 	m_cloud.clouds->setHeight(100.0f);
 	m_cloud.clouds->update(v3f(0, 0, 0), video::SColor(255,240,240,255));

src/gui/guiEngine.h

@@ -53,6 +53,7 @@ struct image_definition {
 class GUIEngine;
 class RenderingEngine;
 class MainMenuScripting;
+class IWritableShaderSource;
 struct MainMenuData;
 
 /******************************************************************************/
@@ -188,7 +189,7 @@ class GUIEngine {
 	/** texture source */
 	std::unique_ptr<ISimpleTextureSource> m_texture_source;
 	/** shader source */
-	std::unique_ptr<IShaderSource>        m_shader_source;
+	std::unique_ptr<IWritableShaderSource> m_shader_source;
 	/** sound manager */
 	std::unique_ptr<ISoundManager>        m_sound_manager;