filter-blur: Switch to Kernel Array instead of Kernel Texture

This speeds up Gaussian Blur and Linear Gaussian Blur drastically reduces time spent reading textures and instead uses existing registers - maximizing time spent reading the actual image texture.

See Also: #21 Blur Quality

data/effects/blur.effect

@@ -10,9 +10,7 @@ uniform int u_diameter;
 uniform float2 u_texelDelta;
 
 // Kernel Settings
-//uniform float registerkernel[25];
+uniform float4 kernel[8]; // max kernel radius 31+center.
-uniform texture2d kernel;
-uniform float2 kernelTexel;
 
 // Bilateral Settings
 uniform float bilateralSmoothing;
@@ -53,6 +51,11 @@ VertDataOut VSDefault(VertDataIn vtx)
 	return vert_out;
 }
 
+/// Utility
+float GetKernelAt(int i) {
+	return ((float[4])(kernel[floor(i/4)]))[i%4];
+}
+
 /// Blur: Box
 float4 PSBoxBlur(VertDataOut vtx) : TARGET {
 	float4 origin = u_image.SampleLevel(pointSampler, vtx.uv, 0);
@@ -131,14 +134,13 @@ technique BoxLinear
 }
 
 /// Blur: Gaussian
-// ToDo: Switch to array Kernel instead of Texture kernel.
 float4 PSGaussianBlur(VertDataOut vtx) : TARGET {
 	float2 uvOffset = float2(0, 0);
 	float4 final = u_image.SampleLevel(pointSampler, vtx.uv, 0)
-		* kernel.SampleLevel(pointSampler, (float2(0, u_radius - 1) * kernelTexel), 0).r;
+		* GetKernelAt(0);
 	for (int k = 1; k <= u_radius; k++) {
 		uvOffset += u_texelDelta;
-		float l_g = kernel.SampleLevel(pointSampler, (float2(k, u_radius - 1) * kernelTexel), 0).r;
+		float l_g = GetKernelAt(k);
 		float4 l_p = u_image.SampleLevel(pointSampler, vtx.uv + uvOffset, 0);
 		float4 l_n = u_image.SampleLevel(pointSampler, vtx.uv - uvOffset, 0);
 		final += (l_p + l_n) * l_g;
@@ -180,15 +182,15 @@ float4 PSGaussianLinearBlur(VertDataOut vtx) : TARGET {
 	// [-2, -1,  0, +1, +2]
 	//   ^-S-^   S   ^-S-^
 	// Total Samples: 3 (n+1)
-	
+
 	float4 origin = u_image.SampleLevel(pointSampler, vtx.uv, 0);
-	float4 final = origin * kernel.SampleLevel(pointSampler, (float2(0, u_radius - 1) * kernelTexel), 0).r;
+	float4 final = origin * GetKernelAt(0);
 	float2 halfTexelDelta = u_texelDelta / 2.0;
 
 	for (int k = 1; k < u_radius; k+=2) {
 		float2 offset = k * u_texelDelta + halfTexelDelta;
-		float l_g0 = kernel.SampleLevel(pointSampler, (float2(k, u_radius - 1) * kernelTexel), 0).r;
+		float l_g0 = GetKernelAt(k);
-		float l_g1 = kernel.SampleLevel(pointSampler, (float2(k + 1, u_radius - 1) * kernelTexel), 0).r;
+		float l_g1 = GetKernelAt(k +1);
 		float4 l_p = u_image.SampleLevel(linearSampler, vtx.uv + offset, 0);
 		float4 l_n = u_image.SampleLevel(linearSampler, vtx.uv - offset, 0);
 		final += (l_p + l_n) * l_g0;
@@ -199,7 +201,7 @@ float4 PSGaussianLinearBlur(VertDataOut vtx) : TARGET {
 		// Odd numbers require treatment of ends.
 		float4 left = u_image.SampleLevel(pointSampler, vtx.uv + u_texelDelta * u_radius, 0);
 		float4 right = u_image.SampleLevel(pointSampler, vtx.uv - u_texelDelta * u_radius, 0);
-		float krn = kernel.SampleLevel(pointSampler, (float2(u_radius, u_radius - 1) * kernelTexel), 0).r;
+		float krn = GetKernelAt(u_radius);
 		final += (left + right) * krn;
 	}
 

source/filter-blur.cpp

@@ -120,18 +120,12 @@ bool filter::blur::blur_instance::apply_bilateral_param()
 	return true;
 }
 
-bool filter::blur::blur_instance::apply_gaussian_param()
+bool filter::blur::blur_instance::apply_gaussian_param(uint8_t width)
 {
-	std::shared_ptr<gs::texture> kernel = filter::blur::blur_factory::get()->get_kernel(filter::blur::type::Gaussian);
+	auto kernel = filter::blur::blur_factory::get()->get_gaussian_kernel(width);
 
 	if (blur_effect->has_parameter("kernel")) {
-		blur_effect->get_parameter("kernel").set_texture(kernel);
+		blur_effect->get_parameter("kernel").set_float_array(&(kernel->front()), kernel->size());
-	}
-
-	if (blur_effect->has_parameter("kernelTexel")) {
-		float_t wb = 1.0f / kernel->get_width();
-		float_t hb = 1.0f / kernel->get_height();
-		blur_effect->get_parameter("kernelTexel").set_float2(wb, hb);
 	}
 
 	return true;
@@ -604,7 +598,7 @@ void filter::blur::blur_instance::video_render(gs_effect_t* effect)
 	}
 #pragma endregion RGB->YUV
 
-#pragma region blur
+#pragma region Blur
 	// Set up camera stuff
 	gs_set_cull_mode(GS_NEITHER);
 	gs_reset_blend_state();
@@ -630,7 +624,7 @@ void filter::blur::blur_instance::video_render(gs_effect_t* effect)
 
 		if (!apply_shared_param(intermediate, xpel, ypel))
 			break;
-		apply_gaussian_param();
+		apply_gaussian_param(this->size);
 		apply_bilateral_param();
 
 		gs_texrender_reset(rt);
@@ -853,11 +847,13 @@ void filter::blur::blur_factory::generate_gaussian_kernels()
 	// 2D texture, horizontal is value, vertical is kernel size.
 	size_t size_power_of_two = size_t(pow(2, util::math::get_power_of_two_exponent_ceil(max_kernel_size)));
 
-	std::vector<float_t> texture_Data(size_power_of_two * size_power_of_two);
+	std::vector<float_t>                  texture_data(size_power_of_two * size_power_of_two);
-	std::vector<float_t> math_data(size_power_of_two);
+	std::vector<float_t>                  math_data(size_power_of_two);
+	std::shared_ptr<std::vector<float_t>> kernel_data;
 
 	for (size_t width = 1; width <= max_kernel_size; width++) {
-		size_t v = (width - 1) * size_power_of_two;
+		size_t v    = (width - 1) * size_power_of_two;
+		kernel_data = std::make_shared<std::vector<float_t>>(size_power_of_two);
 
 		// Calculate and normalize
 		float_t sum = 0;
@@ -869,13 +865,16 @@ void filter::blur::blur_factory::generate_gaussian_kernels()
 		// Normalize to Texture Buffer
 		double_t inverse_sum = 1.0 / sum;
 		for (size_t p = 0; p <= width; p++) {
-			texture_Data[v + p] = float_t(math_data[p] * inverse_sum);
+			texture_data[v + p] = float_t(math_data[p] * inverse_sum);
+			kernel_data->at(p)  = texture_data[v + p];
 		}
+
+		gaussian_kernels.insert({uint8_t(width), kernel_data});
 	}
 
 	// Create Texture
 	try {
-		auto texture_buffer = reinterpret_cast<uint8_t*>(texture_Data.data());
+		auto texture_buffer = reinterpret_cast<uint8_t*>(texture_data.data());
 		auto unsafe_buffer  = const_cast<const uint8_t**>(&texture_buffer);
 
 		kernels.insert_or_assign(filter::blur::type::Gaussian,
@@ -1046,6 +1045,11 @@ std::shared_ptr<gs::texture> filter::blur::blur_factory::get_kernel(filter::blur
 	return kernels.at(type);
 }
 
+std::shared_ptr<std::vector<float_t>> filter::blur::blur_factory::get_gaussian_kernel(uint8_t size)
+{
+	return gaussian_kernels.at(size);
+}
+
 obs_scene_t* filter::blur::blur_factory::get_scene(std::string name)
 {
 	auto kv = scenes.find(name);

source/filter-blur.h

@@ -111,7 +111,7 @@ namespace filter {
 
 			bool apply_shared_param(gs_texture_t* input, float texelX, float texelY);
 			bool apply_bilateral_param();
-			bool apply_gaussian_param();
+			bool apply_gaussian_param(uint8_t width);
 			bool apply_mask_parameters(std::shared_ptr<gs::effect> effect, gs_texture_t* original_texture,
 									   gs_texture_t* blurred_texture);
 
@@ -143,6 +143,7 @@ namespace filter {
 
 			std::shared_ptr<gs::effect>                                blur_effect;
 			std::map<filter::blur::type, std::shared_ptr<gs::texture>> kernels;
+			std::map<uint8_t, std::shared_ptr<std::vector<float_t>>>   gaussian_kernels;
 
 			std::map<std::string, obs_scene_t*> scenes;
 
@@ -188,6 +189,8 @@ namespace filter {
 
 			std::shared_ptr<gs::texture> get_kernel(filter::blur::type type);
 
+			std::shared_ptr<std::vector<float_t>> get_gaussian_kernel(uint8_t size);
+
 			obs_scene_t* get_scene(std::string name);
 
 			void enum_scenes(std::function<bool(obs_scene_t*)> fnc);