ssao - some configuration exposed

data/shaders/ssao_blit.hlsl

@@ -2,6 +2,7 @@
 
 cbuffer Data : register(b4) {
 	uint u_downscale;
+	float u_depth_diff_weight;
 	TextureHandle u_ssao_buf;
 	TextureHandle u_depthbuffer; // full-size
 	TextureHandle u_depthbuffer_small; // downscaled, if available
@@ -43,19 +44,24 @@ void main(uint3 thread_id : SV_DispatchThreadID) {
 
 		// compute weights as combination of depth differences and bilinear coefs
 		// depth difference added to bilinear coefs to fixed artifacts at depth discontinuities
-		float w00 = r00 - r00 * abs(d - d00);
-		float w10 = r10 - r10 * abs(d - d10);
-		float w01 = r01 - r01 * abs(d - d01);
-		float w11 = r11 - r11 * abs(d - d11);
+		float w00 = saturate(r00 - saturate(r00 * abs(d - d00) * u_depth_diff_weight));
+		float w10 = saturate(r10 - saturate(r10 * abs(d - d10) * u_depth_diff_weight));
+		float w01 = saturate(r01 - saturate(r01 * abs(d - d01) * u_depth_diff_weight));
+		float w11 = saturate(r11 - saturate(r11 * abs(d - d11) * u_depth_diff_weight));
 
 		ssao = ssao00 * w00
 			+ ssao10 * w10
 			+ ssao01 * w01
 			+ ssao11 * w11;
 
-		// normalize weight (because of depth differences)
 		float sum_w = w00 + w01 + w10 + w11;
-		ssao /= sum_w; 
+		if (sum_w < 10e-6) {
+			// our depth is not close to any from the four sampled depths, just use the first one
+			ssao = ssao00;
+		} else {
+			// normalize weight (because of depth differences)
+			ssao = saturate(ssao / (sum_w + 10e-6)); 
+		}
 	} else {
 		// ssao is at full resolution, just sample it
 		float2 uv = (thread_id.xy + 0.5) * Global_rcp_framebuffer_size;

src/renderer/postprocess.h

@@ -706,6 +706,7 @@ struct SSAO : public RenderPlugin {
 	bool m_enabled = true;
 	u32 m_blur_iterations = 3;
 	u32 m_downscale = 1;
+	float m_depth_diff_weight = 2;
 	float m_radius = 0.4f;
 	float m_intensity = 1.f;
 
@@ -729,9 +730,10 @@ struct SSAO : public RenderPlugin {
 	void debugUI(Pipeline& pipeline) override {
 		if (ImGui::BeginMenu("SSAO")) {
 			ImGui::Checkbox("Enabled", &m_enabled);
-			ImGui::DragFloat("Radius", &m_radius);
-			ImGui::DragFloat("Intensity", &m_intensity);
-			ImGui::DragInt("Blur iterations", (i32*)&m_blur_iterations);
+			ImGui::DragFloat("Radius", &m_radius, 0.1f, FLT_MIN, FLT_MAX);
+			ImGui::DragFloat("Intensity", &m_intensity, 0.1f, FLT_MIN, FLT_MAX);
+			ImGui::DragFloat("Depth difference weight", &m_depth_diff_weight, 0.1f, FLT_MIN, FLT_MAX);
+			ImGui::DragInt("Blur iterations", (i32*)&m_blur_iterations, 1, 0, 50);
 			const char* downscale_values[] = { "Disabled", "2x", "4x" };
 			ImGui::TextUnformatted("Downscale");
 			for (const char*& v : downscale_values) {
@@ -861,12 +863,14 @@ struct SSAO : public RenderPlugin {
 
 		struct {
 			u32 downscale;
+			float depth_diff_weight;
 			gpu::BindlessHandle ssao_buf;
 			gpu::BindlessHandle depth_buffer;
 			gpu::BindlessHandle depth_buffer_small;
 			gpu::RWBindlessHandle gbufferB;
 		} udata2 = {
 			.downscale = m_downscale,
+			.depth_diff_weight = m_depth_diff_weight,
 			.ssao_buf = pipeline.toBindless(ssao_rb, stream),
 			.depth_buffer = pipeline.toBindless(gbuffer.DS, stream),
 			.depth_buffer_small = pipeline.toBindless(depth_buffer, stream),