From f11eff0e9667bce3e77aff9bcad188633b13902c Mon Sep 17 00:00:00 2001
From: Martin Opat <martinopat.opat@gmail.com>
Date: Wed, 15 Jan 2025 19:53:50 +0100
Subject: [PATCH] Added alpha accum gui param

---
 src/consts.cu                 | 1 +
 src/consts.h                  | 4 +++-
 src/gui/input/Widget.cpp      | 3 +++
 src/gui/input/Widget.h        | 1 +
 src/illumination/Raycaster.cu | 2 +-
 5 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/consts.cu b/src/consts.cu
index ed48441..3e3b336 100644
--- a/src/consts.cu
+++ b/src/consts.cu
@@ -51,6 +51,7 @@ void copyConstantsToDevice() {
 __device__ float d_opacityK;
 __device__ float d_sigmoidShift;
 __device__ float d_sigmoidExp;
+__device__ float d_alphaAcumLimit;
 __device__ int d_tfComboSelected;
 __device__ int d_tfComboSelectedColor;
 __device__ float d_opacityConst;
diff --git a/src/consts.h b/src/consts.h
index 7d739a3..93b04f2 100644
--- a/src/consts.h
+++ b/src/consts.h
@@ -32,7 +32,7 @@ const float MAX_SPEED = 14.0f;
 // --------------------------- Raycasting Constants ---------------------------
 const int SAMPLES_PER_PIXEL = 4;
 
-const float alphaAcumLimit = 0.4f;   // TODO: Atm, this only works with sigmoid
+// const float alphaAcumLimit = 0.4f;   // TODO: Atm, this only works with sigmoid
 const float minAllowedDensity = 0.001f;
 
 const float stepSize = 0.02f;
@@ -67,6 +67,8 @@ extern __device__ float d_opacityK;
 // sigmoid function variables
 extern __device__ float d_sigmoidShift;
 extern __device__ float d_sigmoidExp;
+// alpha accumulation limit
+extern __device__ float d_alphaAcumLimit;
 // combo box index
 extern __device__ int d_tfComboSelected;
 extern __device__ int d_tfComboSelectedColor;
diff --git a/src/gui/input/Widget.cpp b/src/gui/input/Widget.cpp
index 6762b2b..a49a50c 100644
--- a/src/gui/input/Widget.cpp
+++ b/src/gui/input/Widget.cpp
@@ -29,6 +29,7 @@ Widget::Widget(GLFWwindow* window) {
   this->opacityK = 0;
   this->sigmoidShift = 0.5f;
   this->sigmoidExp = -250.0f;
+  this->alphaAcumLimit = 0.4f;
   this->tfComboSelected = 0;
   this->opacityConst = 100;
 };
@@ -53,6 +54,7 @@ void Widget::tick(double fps) {
   ImGui::DragInt("Gradient exp. (log [1e-10, 1])", &this->opacityK, 1, 0, 100, "%d%%", ImGuiSliderFlags_AlwaysClamp);
   ImGui::DragFloat("sigmoidShift", &this->sigmoidShift, 0.01f, 0.0f, 1.0f, "%.2f");
   ImGui::InputFloat("sigmoidExp", &this->sigmoidExp, 10.0f, 100.0f, "%.0f");
+  ImGui::DragFloat("Alpha accumulation limit", &this->alphaAcumLimit, 0.01f, 0.0f, 1.0f, "%.2f");
   ImGui::DragInt("Opacity constant (log [1e-5, 1])", &this->opacityConst, 1, 0, 100, "%d%%", ImGuiSliderFlags_AlwaysClamp);
   
   // the items[] contains the entries for the combobox. The selected index is stored as an int on this->tfComboSelected
@@ -130,6 +132,7 @@ void Widget::copyToDevice() {
 
   cudaMemcpyToSymbol(&d_sigmoidShift, &this->sigmoidShift, sizeof(float));
   cudaMemcpyToSymbol(&d_sigmoidExp, &this->sigmoidExp, sizeof(float));
+  cudaMemcpyToSymbol(&d_alphaAcumLimit, &this->alphaAcumLimit, sizeof(float));
   cudaMemcpyToSymbol(&d_tfComboSelected, &this->tfComboSelected, sizeof(int));
 
   this->opacityConstReal = std::pow(10.0f, (-5 + 0.05 * this->opacityConst));
diff --git a/src/gui/input/Widget.h b/src/gui/input/Widget.h
index ac2cbcd..73f5cc6 100644
--- a/src/gui/input/Widget.h
+++ b/src/gui/input/Widget.h
@@ -24,6 +24,7 @@ public:
   float opacityKReal;
   float sigmoidShift;
   float sigmoidExp;
+  float alphaAcumLimit;
   int opacityConst;
   float opacityConstReal;
 
diff --git a/src/illumination/Raycaster.cu b/src/illumination/Raycaster.cu
index ba72985..9e6db0d 100644
--- a/src/illumination/Raycaster.cu
+++ b/src/illumination/Raycaster.cu
@@ -84,7 +84,7 @@ __global__ void raycastKernel(float* volumeData, FrameBuffer framebuffer, const
           float alphaAccum = 0.0f;
 
           float t = tNear;  // Front to back
-          while (t < tFar && alphaAccum < alphaAcumLimit) {
+          while (t < tFar && alphaAccum < d_alphaAcumLimit) {
               Point3 pos = d_cameraPos + rayDir * t;
 
               // Convert to volume indices