Improve bloom effect (#12916)

* Remove the built-in exposure factor of 2.5
* Add physics-based bloom (https://learnopengl.com/Guest-Articles/2022/Phys.-Based-Bloom)
* Add luminance scaling for bloom layer to simulate HDR
* Add setting to control bloom strength

builtin/settingtypes.txt

@@ -470,21 +470,19 @@ enable_bloom (Enable Bloom) bool false
 #    bottom-left - raw base image, bottom-right - bloom texture.
 enable_bloom_debug (Enable Bloom Debug) bool false
 
-#    Set to true to use dedicated texture at each step of bloom effect.
-#    This is a compatibility setting to avoid visual artifacts 
-#    on certain GPUs and video drivers.
-enable_bloom_dedicated_texture (Enable Bloom Dedicated Texture) bool false
-
-#    Set the intensity of bloom
+#    Defines how much bloom is applied to the rendered image
 #    Smaller values make bloom more subtle
 #    Range: from 0.01 to 1.0, default: 0.05
 bloom_intensity (Bloom Intensity) float 0.05 0.01 1.0
 
-#    Set the radius of the bloom filter in pixels.
-#    Larger values render more glow around bright objects
-#    at the cost of higher resource consumption.
-#    Range: from 1 to 64, default: 16
-bloom_radius (Bloom Radius) int 16 1 64
+#    Defines the magnitude of bloom overexposure.
+#    Range: from 0.1 to 10.0, default: 1.0
+bloom_strength_factor (Bloom Strength Factor) float 1.0 0.1 10.0
+
+#    Logical value that controls how far the bloom effect spreads
+#    from the bright objects.
+#    Range: from 0.1 to 8, default: 1
+bloom_radius (Bloom Radius) float 1 0.1 8
 
 
 [*Audio]

client/shaders/bloom_downsample/opengl_fragment.glsl

@@ -0,0 +1,37 @@
+// based on Phys.Bloom OpenGL tutorial https://learnopengl.com/Guest-Articles/2022/Phys.-Based-Bloom
+// and ACM Siggraph talk in 2014 by Jorge Jimenez for Call of Duty: Advanced Warfare.
+#define rendered texture0
+
+uniform sampler2D rendered;
+uniform vec2 texelSize0;
+
+#ifdef GL_ES
+varying mediump vec2 varTexCoord;
+#else
+centroid varying vec2 varTexCoord;
+#endif
+
+void main(void)
+{
+	vec2 tx = 2.0 * texelSize0;
+	vec3 a = texture2D(rendered, varTexCoord.st + vec2(-1., -1.) * tx).rgb;
+	vec3 b = texture2D(rendered, varTexCoord.st + vec2(0., -1.) * tx).rgb;
+	vec3 c = texture2D(rendered, varTexCoord.st + vec2(1., -1.) * tx).rgb;
+	vec3 d = texture2D(rendered, varTexCoord.st + vec2(-1., 0.) * tx).rgb;
+	vec3 e = texture2D(rendered, varTexCoord.st + vec2(0., 0.) * tx).rgb;
+	vec3 f = texture2D(rendered, varTexCoord.st + vec2(1., 0.) * tx).rgb;
+	vec3 g = texture2D(rendered, varTexCoord.st + vec2(-1., 1.) * tx).rgb;
+	vec3 h = texture2D(rendered, varTexCoord.st + vec2(0., 1.) * tx).rgb;
+	vec3 i = texture2D(rendered, varTexCoord.st + vec2(1., 1.) * tx).rgb;
+	vec3 j = texture2D(rendered, varTexCoord.st + vec2(-0.5, -0.5) * tx).rgb;
+	vec3 k = texture2D(rendered, varTexCoord.st + vec2(0.5, -0.5) * tx).rgb;
+	vec3 l = texture2D(rendered, varTexCoord.st + vec2(-0.5, 0.5) * tx).rgb;
+	vec3 m = texture2D(rendered, varTexCoord.st + vec2(-0.5, 0.5) * tx).rgb;
+
+	vec3 color =
+		(a + c + g + i) * 0.03125 +
+		(b + d + f + h) * 0.0625 +
+		(e + j + k + l + m) * 0.125;
+
+	gl_FragColor = max(vec4(color, 1.0), 1e-4);
+}

client/shaders/bloom_downsample/opengl_vertex.glsl

@@ -0,0 +1,11 @@
+#ifdef GL_ES
+varying mediump vec2 varTexCoord;
+#else
+centroid varying vec2 varTexCoord;
+#endif
+
+void main(void)
+{
+	varTexCoord.st = inTexCoord0.st;
+	gl_Position = inVertexPosition;
+}

client/shaders/bloom_upsample/opengl_fragment.glsl

@@ -0,0 +1,35 @@
+#define current texture0
+#define previous texture1
+
+uniform sampler2D current;
+uniform sampler2D previous;
+uniform vec2 texelSize0;
+uniform mediump float bloomRadius;
+
+#ifdef GL_ES
+varying mediump vec2 varTexCoord;
+#else
+centroid varying vec2 varTexCoord;
+#endif
+
+void main(void)
+{
+	vec2 offset = bloomRadius * texelSize0;
+
+	vec3 a = texture2D(previous, varTexCoord.st + vec2(-1., -1.) * offset).rgb;
+	vec3 b = texture2D(previous, varTexCoord.st + vec2(0., -1.) * offset).rgb;
+	vec3 c = texture2D(previous, varTexCoord.st + vec2(1., -1.) * offset).rgb;
+	vec3 d = texture2D(previous, varTexCoord.st + vec2(-1., 0.) * offset).rgb;
+	vec3 e = texture2D(previous, varTexCoord.st + vec2(0., 0.) * offset).rgb;
+	vec3 f = texture2D(previous, varTexCoord.st + vec2(1., 0.) * offset).rgb;
+	vec3 g = texture2D(previous, varTexCoord.st + vec2(-1., 1.) * offset).rgb;
+	vec3 h = texture2D(previous, varTexCoord.st + vec2(0., 1.) * offset).rgb;
+	vec3 i = texture2D(previous, varTexCoord.st + vec2(1., 1.) * offset).rgb;
+
+	vec3 base = texture2D(current, varTexCoord.st).rgb;
+
+	gl_FragColor = max(vec4(base +
+			(a + c + g + i) * 0.0625 +
+			(b + d + f + h) * 0.125 +
+			e * 0.25, 1.), 1e-4);
+}

client/shaders/bloom_upsample/opengl_vertex.glsl

@@ -0,0 +1,11 @@
+#ifdef GL_ES
+varying mediump vec2 varTexCoord;
+#else
+centroid varying vec2 varTexCoord;
+#endif
+
+void main(void)
+{
+	varTexCoord.st = inTexCoord0.st;
+	gl_Position = inVertexPosition;
+}

client/shaders/blur_h/opengl_fragment.glsl

@@ -3,6 +3,7 @@
 uniform sampler2D rendered;
 uniform vec2 texelSize0;
 uniform mediump float bloomRadius;
+uniform mat3 bloomBlurWeights;
 
 #ifdef GL_ES
 varying mediump vec2 varTexCoord;
@@ -10,6 +11,13 @@ varying mediump vec2 varTexCoord;
 centroid varying vec2 varTexCoord;
 #endif
 
+// smoothstep - squared
+float smstsq(float f)
+{
+	f = f * f * (3 - 2 * f);
+	return f;
+}
+
 void main(void)
 {
 	// kernel distance and linear size
@@ -19,8 +27,8 @@ void main(void)
 	vec4 color = vec4(0.);
 	mediump float sum = 0.;
 	for (mediump float i = 0.; i < n; i++) {
-		mediump float weight = pow(1. - (abs(i / bloomRadius - 1.)), 1.3);
-		color += texture2D(rendered, uv).rgba * weight;
+		mediump float weight = smstsq(1. - (abs(i / bloomRadius - 1.)));
+		color.rgb += texture2D(rendered, uv).rgb * weight;
 		sum += weight;
 		uv += vec2(texelSize0.x, 0.);
 	}

client/shaders/blur_v/opengl_fragment.glsl

@@ -3,6 +3,7 @@
 uniform sampler2D rendered;
 uniform vec2 texelSize0;
 uniform mediump float bloomRadius;
+uniform mat3 bloomBlurWeights;
 
 #ifdef GL_ES
 varying mediump vec2 varTexCoord;
@@ -10,6 +11,13 @@ varying mediump vec2 varTexCoord;
 centroid varying vec2 varTexCoord;
 #endif
 
+// smoothstep - squared
+float smstsq(float f)
+{
+	f = f * f * (3 - 2 * f);
+	return f;
+}
+
 void main(void)
 {
 	// kernel distance and linear size
@@ -19,8 +27,8 @@ void main(void)
 	vec4 color = vec4(0.);
 	mediump float sum = 0.;
 	for (mediump float i = 0.; i < n; i++) {
-		mediump float weight = pow(1. - (abs(i / bloomRadius - 1.)), 1.3);
-		color += texture2D(rendered, uv).rgba * weight;
+		mediump float weight = smstsq(1. - (abs(i / bloomRadius - 1.)));
+		color.rgb += texture2D(rendered, uv).rgb * weight;
 		sum += weight;
 		uv += vec2(0., texelSize0.y);
 	}

client/shaders/extract_bloom/opengl_fragment.glsl

@@ -2,7 +2,7 @@
 
 uniform sampler2D rendered;
 uniform mediump float exposureFactor;
-uniform float bloomLuminanceThreshold;
+uniform mediump float bloomStrength;
 
 #ifdef GL_ES
 varying mediump vec2 varTexCoord;
@@ -14,8 +14,14 @@ centroid varying vec2 varTexCoord;
 void main(void)
 {
 	vec2 uv = varTexCoord.st;
-	vec4 color = texture2D(rendered, uv).rgba;
+	vec3 color = texture2D(rendered, uv).rgb;
 	// translate to linear colorspace (approximate)
-	color.rgb = pow(color.rgb, vec3(2.2)) * exposureFactor;
-	gl_FragColor = vec4(color.rgb, 1.0); // force full alpha to avoid holes in the image.
+	color = pow(color, vec3(2.2));
+
+	// Scale colors by luminance to amplify bright colors
+	// in SDR textures.
+	float luminance = dot(color, vec3(0.213, 0.515, 0.072));
+	luminance *= luminance;
+	color *= luminance * exposureFactor * bloomStrength;
+	gl_FragColor = vec4(color, 1.0); // force full alpha to avoid holes in the image.
 }

client/shaders/second_stage/opengl_fragment.glsl

@@ -16,15 +16,14 @@ centroid varying vec2 varTexCoord;
 
 vec4 applyBloom(vec4 color, vec2 uv)
 {
-	float bias = bloomIntensity;
-	vec4 bloom = texture2D(bloom, uv);
+	vec3 light = texture2D(bloom, uv).rgb;
 #ifdef ENABLE_BLOOM_DEBUG
 	if (uv.x > 0.5 && uv.y < 0.5)
-		return vec4(bloom.rgb, color.a);
+		return vec4(light, color.a);
 	if (uv.x < 0.5)
-		return color;
+		return light;
 #endif
-	color.rgb = mix(color.rgb, bloom.rgb, bias);
+	color.rgb = mix(color.rgb, light, bloomIntensity);
 	return color;
 }
 
@@ -86,8 +85,6 @@ void main(void)
 	{
 #if ENABLE_TONE_MAPPING
 		color = applyToneMapping(color);
-#else
-		color.rgb /= 2.5; // default exposure factor, see also RenderingEngine::DEFAULT_EXPOSURE_FACTOR;
 #endif
 	}
 

src/client/game.cpp

@@ -432,6 +432,8 @@ class GameGlobalShaderConstantSetter : public IShaderConstantSetter
 	bool m_bloom_enabled;
 	CachedPixelShaderSetting<float> m_bloom_intensity_pixel;
 	float m_bloom_intensity;
+	CachedPixelShaderSetting<float> m_bloom_strength_pixel;
+	float m_bloom_strength;
 	CachedPixelShaderSetting<float> m_bloom_radius_pixel;
 	float m_bloom_radius;
 
@@ -444,8 +446,10 @@ public:
 			m_user_exposure_factor = g_settings->getFloat("exposure_factor", 0.1f, 10.0f);
 		if (name == "bloom_intensity")
 			m_bloom_intensity = g_settings->getFloat("bloom_intensity", 0.01f, 1.0f);
+		if (name == "bloom_strength_factor")
+			m_bloom_strength = RenderingEngine::BASE_BLOOM_STRENGTH * g_settings->getFloat("bloom_strength_factor", 0.1f, 10.0f);
 		if (name == "bloom_radius")
-			m_bloom_radius = g_settings->getFloat("bloom_radius", 1.0f, 64.0f);
+			m_bloom_radius = g_settings->getFloat("bloom_radius", 0.1f, 8.0f);
 	}
 
 	static void settingsCallback(const std::string &name, void *userdata)
@@ -479,17 +483,20 @@ public:
 		m_texel_size0("texelSize0"),
 		m_exposure_factor_pixel("exposureFactor"),
 		m_bloom_intensity_pixel("bloomIntensity"),
+		m_bloom_strength_pixel("bloomStrength"),
 		m_bloom_radius_pixel("bloomRadius")
 	{
 		g_settings->registerChangedCallback("enable_fog", settingsCallback, this);
 		g_settings->registerChangedCallback("exposure_factor", settingsCallback, this);
 		g_settings->registerChangedCallback("bloom_intensity", settingsCallback, this);
+		g_settings->registerChangedCallback("bloom_strength_factor", settingsCallback, this);
 		g_settings->registerChangedCallback("bloom_radius", settingsCallback, this);
 		m_fog_enabled = g_settings->getBool("enable_fog");
 		m_user_exposure_factor = g_settings->getFloat("exposure_factor", 0.1f, 10.0f);
 		m_bloom_enabled = g_settings->getBool("enable_bloom");
 		m_bloom_intensity = g_settings->getFloat("bloom_intensity", 0.01f, 1.0f);
-		m_bloom_radius = g_settings->getFloat("bloom_radius", 1.0f, 64.0f);
+		m_bloom_strength = RenderingEngine::BASE_BLOOM_STRENGTH * g_settings->getFloat("bloom_strength_factor", 0.1f, 10.0f);
+		m_bloom_radius = g_settings->getFloat("bloom_radius", 0.1f, 8.0f);
 	}
 
 	~GameGlobalShaderConstantSetter()
@@ -567,14 +574,15 @@ public:
 
 		m_texel_size0.set(m_texel_size0_values.data(), services);
 
-		float exposure_factor = RenderingEngine::DEFAULT_EXPOSURE_FACTOR * m_user_exposure_factor;
+		float exposure_factor = m_user_exposure_factor;
 		if (std::isnan(exposure_factor))
-			exposure_factor = RenderingEngine::DEFAULT_EXPOSURE_FACTOR;
+			exposure_factor = 1.0f;
 		m_exposure_factor_pixel.set(&exposure_factor, services);
 
 		if (m_bloom_enabled) {
 			m_bloom_intensity_pixel.set(&m_bloom_intensity, services);
 			m_bloom_radius_pixel.set(&m_bloom_radius, services);
+			m_bloom_strength_pixel.set(&m_bloom_strength, services);
 		}
 	}
 

src/client/render/pipeline.h

@@ -390,9 +390,10 @@ public:
 	 * @return RenderStep* Pointer to the created step for further configuration.
 	 */
 	template<typename T, typename... Args>
-	RenderStep *addStep(Args&&... args) {
+	T *addStep(Args&&... args) {
 		T* result = own(std::make_unique<T>(std::forward<Args>(args)...));
-		return addStep(result);
+		addStep(result);
+		return result;
 	}
 
 	RenderSource *getInput();

src/client/render/secondstage.cpp

@@ -115,8 +115,8 @@ RenderStep *addPostProcessing(RenderPipeline *pipeline, RenderStep *previousStep
 	static const u8 TEXTURE_COLOR = 0;
 	static const u8 TEXTURE_DEPTH = 1;
 	static const u8 TEXTURE_BLOOM = 2;
-	static const u8 TEXTURE_BLUR = 3;
-	static const u8 TEXTURE_BLUR_SECONDARY = 4;
+	static const u8 TEXTURE_BLOOM_DOWN = 10;
+	static const u8 TEXTURE_BLOOM_UP = 20;
 
 	buffer->setTexture(TEXTURE_COLOR, scale, "3d_render", color_format);
 	buffer->setTexture(TEXTURE_DEPTH, scale, "3d_depthmap", depth_format);
@@ -124,39 +124,56 @@ RenderStep *addPostProcessing(RenderPipeline *pipeline, RenderStep *previousStep
 	// attach buffer to the previous step
 	previousStep->setRenderTarget(pipeline->createOwned<TextureBufferOutput>(buffer, std::vector<u8> { TEXTURE_COLOR }, TEXTURE_DEPTH));
 
+	// shared variables
+	u32 shader_id;
+
 	// post-processing stage
 	// set up bloom
 	if (g_settings->getBool("enable_bloom")) {
 
-		buffer->setTexture(TEXTURE_BLUR, scale * 0.5, "blur", color_format);
-		buffer->setTexture(TEXTURE_BLOOM, scale * 0.5, "bloom", color_format);
-		u8 bloom_input_texture = TEXTURE_BLOOM;
 
-		if (g_settings->getBool("enable_bloom_dedicated_texture")) {
-			buffer->setTexture(TEXTURE_BLUR_SECONDARY, scale * 0.5, "blur2", color_format);
-			bloom_input_texture = TEXTURE_BLUR_SECONDARY;
+		buffer->setTexture(TEXTURE_BLOOM, scale, "bloom", color_format);
+
+		const u8 MIPMAP_LEVELS = 4;
+		v2f downscale = scale * 0.5;
+		for (u8 i = 0; i < MIPMAP_LEVELS; i++) {
+			buffer->setTexture(TEXTURE_BLOOM_DOWN + i, downscale, std::string("bloom_down") + std::to_string(i), color_format);
+			buffer->setTexture(TEXTURE_BLOOM_UP + i, downscale, std::string("bloom_up") + std::to_string(i), color_format);
+			downscale *= 0.5;
 		}
 
 		// get bright spots
 		u32 shader_id = client->getShaderSource()->getShader("extract_bloom", TILE_MATERIAL_PLAIN, NDT_MESH);
 		RenderStep *extract_bloom = pipeline->addStep<PostProcessingStep>(shader_id, std::vector<u8> { TEXTURE_COLOR });
 		extract_bloom->setRenderSource(buffer);
-		extract_bloom->setRenderTarget(pipeline->createOwned<TextureBufferOutput>(buffer, bloom_input_texture));
-		// horizontal blur
-		shader_id = client->getShaderSource()->getShader("blur_h", TILE_MATERIAL_PLAIN, NDT_MESH);
-		RenderStep *blur_h = pipeline->addStep<PostProcessingStep>(shader_id, std::vector<u8> { bloom_input_texture });
-		blur_h->setRenderSource(buffer);
-		blur_h->setRenderTarget(pipeline->createOwned<TextureBufferOutput>(buffer, TEXTURE_BLUR));
-		// vertical blur
-		shader_id = client->getShaderSource()->getShader("blur_v", TILE_MATERIAL_PLAIN, NDT_MESH);
-		RenderStep *blur_v = pipeline->addStep<PostProcessingStep>(shader_id, std::vector<u8> { TEXTURE_BLUR });
-		blur_v->setRenderSource(buffer);
-		blur_v->setRenderTarget(pipeline->createOwned<TextureBufferOutput>(buffer, TEXTURE_BLOOM));
+		extract_bloom->setRenderTarget(pipeline->createOwned<TextureBufferOutput>(buffer, TEXTURE_BLOOM));
+
+		// downsample
+		shader_id = client->getShaderSource()->getShader("bloom_downsample", TILE_MATERIAL_PLAIN, NDT_MESH);
+		u8 source = TEXTURE_BLOOM;
+		for (u8 i = 0; i < MIPMAP_LEVELS; i++) {
+			auto step = pipeline->addStep<PostProcessingStep>(shader_id, std::vector<u8> { source });
+			step->setRenderSource(buffer);
+			step->setBilinearFilter(0, true);
+			step->setRenderTarget(pipeline->createOwned<TextureBufferOutput>(buffer, TEXTURE_BLOOM_DOWN + i));
+			source = TEXTURE_BLOOM_DOWN + i;
+		}
+
+		// upsample
+		shader_id = client->getShaderSource()->getShader("bloom_upsample", TILE_MATERIAL_PLAIN, NDT_MESH);
+		for (u8 i = MIPMAP_LEVELS - 1; i > 0; i--) {
+			auto step = pipeline->addStep<PostProcessingStep>(shader_id, std::vector<u8> { u8(TEXTURE_BLOOM_DOWN + i - 1), source });
+			step->setRenderSource(buffer);
+			step->setBilinearFilter(0, true);
+			step->setBilinearFilter(1, true);
+			step->setRenderTarget(pipeline->createOwned<TextureBufferOutput>(buffer, u8(TEXTURE_BLOOM_UP + i - 1)));
+			source = TEXTURE_BLOOM_UP + i - 1;
+		}
 	}
 
 	// final post-processing
-	u32 shader_id = client->getShaderSource()->getShader("second_stage", TILE_MATERIAL_PLAIN, NDT_MESH);
-	PostProcessingStep *effect = pipeline->createOwned<PostProcessingStep>(shader_id, std::vector<u8> { TEXTURE_COLOR, TEXTURE_BLOOM });
+	shader_id = client->getShaderSource()->getShader("second_stage", TILE_MATERIAL_PLAIN, NDT_MESH);
+	PostProcessingStep *effect = pipeline->createOwned<PostProcessingStep>(shader_id, std::vector<u8> { TEXTURE_COLOR, TEXTURE_BLOOM_UP });
 	pipeline->addStep(effect);
 	effect->setBilinearFilter(1, true); // apply filter to the bloom
 	effect->setRenderSource(buffer);

src/client/renderingengine.cpp

@@ -56,6 +56,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #endif
 
 RenderingEngine *RenderingEngine::s_singleton = nullptr;
+const float RenderingEngine::BASE_BLOOM_STRENGTH = 8.0f;
 
 
 static gui::GUISkin *createSkin(gui::IGUIEnvironment *environment,

src/client/renderingengine.h

@@ -46,9 +46,7 @@ class RenderingCore;
 class RenderingEngine
 {
 public:
-	/// Default color factor before applying effects like bloom or tomemapping
-	/// this is derived from tonemapping code and tuned empirically
-	static constexpr float DEFAULT_EXPOSURE_FACTOR = 2.5f;
+	static const float BASE_BLOOM_STRENGTH;
 
 	RenderingEngine(IEventReceiver *eventReceiver);
 	~RenderingEngine();

src/defaultsettings.cpp

@@ -273,9 +273,9 @@ void set_default_settings()
 	settings->setDefault("exposure_factor", "1.0");
 	settings->setDefault("enable_bloom", "false");
 	settings->setDefault("enable_bloom_debug", "false");
-	settings->setDefault("enable_bloom_dedicated_texture", "false");
+	settings->setDefault("bloom_strength_factor", "1.0");
 	settings->setDefault("bloom_intensity", "0.05");
-	settings->setDefault("bloom_radius", "16");
+	settings->setDefault("bloom_radius", "1");
 
 	// Effects Shadows
 	settings->setDefault("enable_dynamic_shadows", "false");