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Played around with transfer function -> needs GUI

This commit is contained in:
Martin Opat 2025-01-11 15:09:42 +01:00
parent 1aa33e8e14
commit 3313e8cf84
1 changed files with 13 additions and 11 deletions
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24
src/illumination/transferFunction.cu
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@ -53,13 +53,13 @@ __device__ float sampleVolumeTrilinear(float* volumeData, const int volW, const
__device__ float opacityFromGradient(const Vec3 &grad) { __device__ float opacityFromGradient(const Vec3 &grad) {
float gradMag = grad.length(); float gradMag = grad.length();
float k = 1e-4f; // tweak (the smaller the value, the less opacity) // TODO: Add a slider for this float k = 1e-6f; // tweak (the smaller the value, the less opacity) // TODO: Add a slider for this
float alpha = 1.0f - expf(-k * gradMag); float alpha = 1.0f - expf(-k * gradMag);
return alpha; return alpha;
} }
__device__ float opacitySigmoid(float normDensity) { __device__ float opacitySigmoid(float val) {
return 1.0f / (1.0f + expf(-250.f * (normDensity - 0.5f))); // TODO: Parametrize and add sliders return 1.0f / (1.0f + expf(-250.f * (val - 0.5f))); // TODO: Parametrize and add sliders
} }
__device__ Color3 colorMap(float normalizedValues, const ColorStop stops[], int N) { __device__ Color3 colorMap(float normalizedValues, const ColorStop stops[], int N) {
@ -98,10 +98,11 @@ __device__ float4 transferFunction(float density, const Vec3& grad, const Point3
// TODO: Add a way to pick different function for alpha // TODO: Add a way to pick different function for alpha
float alpha = opacityFromGradient(grad); float alpha = opacityFromGradient(grad);
alpha = 0.1f; // alpha = 0.1f;
alpha = opacitySigmoid(normDensity); alpha = opacitySigmoid(normDensity);
// alpha = (1.0f - fabs(grad.normalize().dot(rayDir.normalize()))) * 0.8f + 0.2f;
float alphaSample = density * alpha; float alphaSample = density * alpha * 0.1;
// --------------------------- Shading --------------------------- // --------------------------- Shading ---------------------------
// Apply Phong // Apply Phong
@ -120,12 +121,13 @@ __device__ float4 transferFunction(float density, const Vec3& grad, const Point3
// --------------------------- Silhouettes --------------------------- // --------------------------- Silhouettes ---------------------------
// TODO: This is the black silhouette, technically if we are doing alpha based on gradient then it's kind of redundant (?) ... but could also be used for even more pronounced edges // TODO: This is the black silhouette, technically if we are doing alpha based on gradient then it's kind of redundant (?) ... but could also be used for even more pronounced edges
// TODO: Add a way to adjust the treshold (0.2f atm) // TODO: Add a way to adjust the treshold (0.2f atm)
if (grad.length() > epsilon && fabs(grad.normalize().dot(viewDir.normalize())) < 0.2f) { // TODO: I don't think we should literally be doing this => use gradient based opacity => delete the below if-statement
result.x = 0.0f; // if (fabs(grad.normalize().dot(rayDir.normalize())) < 0.2f) {
result.y = 0.0f; // result.x = 0.0f;
result.z = 0.0f; // result.y = 0.0f;
result.w = 1.0f; // result.z = 0.0f;
} // result.w = 1.0f;
// }
return result; return result;
} }