From 4ec94c97879aafef15f7663135745e4ba61e62cf Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Mon, 17 May 2021 00:15:33 +0200
Subject: Extract first public LiterateLB version

---
 tangle/LLBM/volumetric.h | 134 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)
 create mode 100644 tangle/LLBM/volumetric.h

(limited to 'tangle/LLBM/volumetric.h')

diff --git a/tangle/LLBM/volumetric.h b/tangle/LLBM/volumetric.h
new file mode 100644
index 0000000..312d0e8
--- /dev/null
+++ b/tangle/LLBM/volumetric.h
@@ -0,0 +1,134 @@
+#include <cuda-samples/Common/helper_math.h>
+
+#include <LLBM/sdf.h>
+
+__device__ float2 getNormalizedScreenPos(float w, float h, float x, float y) {
+	return make_float2(
+		2.f * (.5f - x/w) * w/h,
+		2.f * (.5f - y/h)
+	);
+}
+
+__device__ float3 getEyeRayDir(float2 screen_pos, float3 eye_pos, float3 eye_target) {
+	const float3 forward = normalize(eye_target - eye_pos);
+	const float3 right   = normalize(cross(make_float3(0.f, 0.f, -1.f), forward));
+	const float3 up      = normalize(cross(forward, right));
+
+	return normalize(screen_pos.x*right + screen_pos.y*up + 4*forward);
+}
+
+__device__ bool aabb(float3 origin, float3 dir, float3 min, float3 max, float& tmin, float& tmax) {
+  float3 invD = make_float3(1./dir.x, 1./dir.y, 1./dir.z);
+  float3 t0s = (min - origin) * invD;
+  float3 t1s = (max - origin) * invD;
+  float3 tsmaller = fminf(t0s, t1s);
+  float3 tbigger  = fmaxf(t0s, t1s);
+  tmin = fmaxf(tmin, fmaxf(tsmaller.x, fmaxf(tsmaller.y, tsmaller.z)));
+  tmax = fminf(tmax, fminf(tbigger.x, fminf(tbigger.y, tbigger.z)));
+  return (tmin < tmax);
+}
+
+__device__ bool aabb(float3 origin, float3 dir, descriptor::CuboidD<3>& cuboid, float& tmin, float& tmax) {
+  return aabb(origin, dir, make_float3(0), make_float3(cuboid.nX,cuboid.nY,cuboid.nZ), tmin, tmax);
+}
+
+struct VolumetricRenderConfig {
+  descriptor::CuboidD<3> cuboid;
+
+  cudaSurfaceObject_t palette;
+  cudaSurfaceObject_t noise;
+
+  float delta = 1;
+  float transparency = 1;
+  float brightness = 1;
+  float3 background = make_float3(22.f / 255.f);
+
+  float3 eye_pos;
+  float3 eye_dir;
+
+  cudaSurfaceObject_t canvas;
+  uint2 canvas_size;
+
+  bool align_slices_to_view = true;
+  bool apply_noise = true;
+  bool apply_blur = true;
+
+  VolumetricRenderConfig(descriptor::CuboidD<3> c):
+    cuboid(c) { }
+};
+
+
+
+template <typename SDF, typename SAMPLER, typename ATTENUATOR>
+__global__ void raymarch(
+  VolumetricRenderConfig config,
+  SDF geometry,
+  SAMPLER sampler,
+  ATTENUATOR attenuator
+) {
+  unsigned int x = blockIdx.x*blockDim.x + threadIdx.x;
+  unsigned int y = blockIdx.y*blockDim.y + threadIdx.y;
+
+  if (x > config.canvas_size.x - 1 || y > config.canvas_size.y - 1) {
+    return;
+  }
+
+  const float2 screen_pos = getNormalizedScreenPos(config.canvas_size.x, config.canvas_size.y, x, y);
+  const float3 ray_dir = getEyeRayDir(screen_pos, config.eye_pos, config.eye_pos + config.eye_dir);
+
+  float3 r = make_float3(0);
+  float  a = 0;
+  
+  float tmin = 0;
+  float tmax = 4000;
+  
+  if (aabb(config.eye_pos, ray_dir, config.cuboid, tmin, tmax)) {
+    float volume_dist = tmax - tmin;
+    float3 geometry_pos = config.eye_pos + tmin*ray_dir;
+    float geometry_dist = approximateDistance(geometry, geometry_pos, ray_dir, 0, volume_dist);
+    geometry_pos += geometry_dist * ray_dir;
+  
+    float jitter = config.align_slices_to_view * (floor(fabs(dot(config.eye_dir, tmin*ray_dir)) / config.delta) * config.delta - tmin)
+                 + config.apply_noise          * config.delta * noiseFromTexture(config.noise, threadIdx.x, threadIdx.y);
+  
+    tmin          += jitter;
+    volume_dist   -= jitter;
+    geometry_dist -= jitter;
+  
+    if (volume_dist > config.delta) {
+      float3 sample_pos = config.eye_pos + tmin * ray_dir;
+      unsigned n_samples = floor(geometry_dist / config.delta);
+      for (unsigned i=0; i < n_samples; ++i) {
+        sample_pos += config.delta * ray_dir;
+        
+        float  sample_value = sampler(sample_pos);
+        float3 sample_color = config.brightness * colorFromTexture(config.palette, sample_value);
+        
+        float sample_attenuation = attenuator(sample_value) * config.transparency;
+        float attenuation = 1 - a;
+        
+        r += attenuation * sample_attenuation * sample_color;
+        a += attenuation * sample_attenuation;
+      }
+    }
+  
+    if (geometry_dist < volume_dist) {
+      float3 n = sdf_normal(geometry, geometry_pos);
+      r = lerp((0.3f + fabs(dot(n, ray_dir))) * make_float3(0.3f), r, a);
+    }
+  } else {
+    a = 0;
+  }
+  
+  if (a < 1) {
+    r += (1 - a) * config.background;
+  }
+
+  uchar4 pixel {
+    static_cast<unsigned char>(clamp(r.x, 0.0f, 1.0f) * 255),
+    static_cast<unsigned char>(clamp(r.y, 0.0f, 1.0f) * 255),
+    static_cast<unsigned char>(clamp(r.z, 0.0f, 1.0f) * 255),
+    255
+  };
+  surf2Dwrite(pixel, config.canvas, x*sizeof(uchar4), y);
+}
-- 
cgit v1.2.3