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Merged
Satvik-Singh192 merged 2 commits into from
Mar 30, 2026
Merged

Feat/render fluids #90

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435ca8b
feat: rendering fluids and buoyancy scenario
Just-Here-TO-Code Mar 30, 2026
00cc464
chore: merge branch 'dev' into feat/render__fluids
Just-Here-TO-Code Mar 30, 2026
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281 changes: 274 additions & 7 deletions renderer/bodymenu.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,8 @@ static float spawnPos[3] = {0.0f, 3.0f, 0.0f};
static float spawnSpeed[3] = {0.0f, 0.0f, 0.0f};
static float spawnForce[3] = {0.0f, 0.0f, 0.0f};
static float spawnMass = 1.0f;
static float spawnDensity = 1.0f;
static float spawnVolume = 0.5235988f;

static float sphereRadius = 0.5f;
static float boxHalfSize[3] = {0.5f, 0.5f, 0.5f};
Expand All @@ -37,6 +39,106 @@ static float rampHalfWidthZ = 1.5f;

static std::vector<std::unique_ptr<Collider>> ownedColliders;

static constexpr float kPi = 3.14159265358979323846f;

static float sphereVolumeFromRadius(float radius)
{
radius = std::max(0.0f, radius);
return (4.0f / 3.0f) * kPi * radius * radius * radius;
}

static float sphereRadiusFromVolume(float volume)
{
volume = std::max(0.0f, volume);
if (volume <= 0.0f)
return 0.0f;
return std::cbrt((3.0f * volume) / (4.0f * kPi));
}

static void setBodyMassAndInertia(Rigidbody &body, float mass)
{
const float MIN_MASS = PHYSICS_EPSILON;
float effective_mass = mass;

if (mass <= 0.0f)
{
effective_mass = 0.0f;
}
else if (mass < MIN_MASS)
{
effective_mass = MIN_MASS;
}

body.inverse_mass = (effective_mass > 0.0f) ? (1.0f / effective_mass) : 0.0f;
const float actual_mass = (body.inverse_mass > 0.0f) ? (1.0f / body.inverse_mass) : 0.0f;

if (!body.collider || actual_mass <= 0.0f)
{
body.inverse_inertia_body = Mat3::identity() * 0.0f;
body.updateworldinvinertia();
return;
}

if (body.collider->type == ShapeType::Sphere)
{
const auto *sphere = static_cast<const SphereCollider *>(body.collider);
const float I = 0.4f * actual_mass * sphere->radius * sphere->radius;
const float invI = (I > PHYSICS_EPSILON) ? (1.0f / I) : 0.0f;
body.inverse_inertia_body = Mat3::diag(invI, invI, invI);
}
else if (body.collider->type == ShapeType::Box)
{
const auto *box = static_cast<const BoxCollider *>(body.collider);
const Vec3 e = box->halfsize * 2.0f;

const float Ix = (actual_mass / 12.0f) * (e.y * e.y + e.z * e.z);
const float Iy = (actual_mass / 12.0f) * (e.x * e.x + e.z * e.z);
const float Iz = (actual_mass / 12.0f) * (e.x * e.x + e.y * e.y);

body.inverse_inertia_body = Mat3::diag(
Ix > PHYSICS_EPSILON ? (1.0f / Ix) : 0.0f,
Iy > PHYSICS_EPSILON ? (1.0f / Iy) : 0.0f,
Iz > PHYSICS_EPSILON ? (1.0f / Iz) : 0.0f);
}
else
{
body.inverse_inertia_body = Mat3::identity() * 0.0f;
}

body.updateworldinvinertia();
}

static bool isBuoyancyHelperWall(const PhysicsWorld &world, const Rigidbody &body)
{
if (!world.enable_buoyancy)
return false;
if (body.inverse_mass != 0.0f)
return false;
if (!body.collider || body.collider->type != ShapeType::Box)
return false;

const Fluid &fluid = world.water_fluid;
const float halfSize = fluid.beaker_half_size;
constexpr float wallThickness = 0.2f;
constexpr float wallHalf = wallThickness / 2.0f;
const float tol = 0.02f;

const auto *box = static_cast<const BoxCollider *>(body.collider);
const Vec3 hs = box->halfsize;

const bool matchesXWall = (std::abs(hs.x - wallHalf) < tol) && (std::abs(hs.y - halfSize) < tol) && (std::abs(hs.z - halfSize) < tol);
const bool matchesZWall = (std::abs(hs.z - wallHalf) < tol) && (std::abs(hs.y - halfSize) < tol) && (std::abs(hs.x - halfSize) < tol);

const float bottomHalfX = std::max(0.01f, halfSize - wallThickness);
const float bottomHalfY = wallHalf;
const float bottomHalfZ = std::max(0.01f, halfSize - wallThickness);
const bool matchesBottom = (std::abs(hs.x - bottomHalfX) < tol) &&
(std::abs(hs.y - bottomHalfY) < tol) &&
(std::abs(hs.z - bottomHalfZ) < tol);

return matchesXWall || matchesZWall || matchesBottom;
}

static void show_tooltip(const char *text)
{
if (ImGui::IsItemHovered(ImGuiHoveredFlags_DelayShort))
Expand Down Expand Up @@ -148,7 +250,29 @@ static float approx_radius_for_new_shape()
static void spawn_body(PhysicsWorld &world)
{
Collider *collider_ptr = nullptr;

int shapeChoice = shapeIndex;
if (world.enable_buoyancy)
{
if (shapeChoice < 0 || shapeChoice > 1)
shapeChoice = 0;
shapeIndex = shapeChoice;

spawnMass = spawnDensity * spawnVolume;
spawnSpeed[0] = spawnSpeed[1] = spawnSpeed[2] = 0.0f;
spawnForce[0] = spawnForce[1] = spawnForce[2] = 0.0f;

if (shapeChoice == 0)
{
sphereRadius = sphereRadiusFromVolume(spawnVolume);
}
else if (shapeChoice == 1)
{
const float h = std::cbrt(std::max(0.0f, spawnVolume) / 8.0f);
boxHalfSize[0] = boxHalfSize[1] = boxHalfSize[2] = h;
}
}

if (world.thermal_spawn_controls.lock_to_basic_shapes && shapeChoice > 1)
{
shapeChoice = std::min(shapeChoice, 1);
Expand Down Expand Up @@ -195,6 +319,90 @@ static void spawn_body(PhysicsWorld &world)
void RenderAddBodyMenuContent(PhysicsWorld &world)
{
ImGui::SeparatorText("Spawn Body");
if (world.enable_buoyancy)
{
if (shapeIndex < 0 || shapeIndex > 1)
shapeIndex = 0;
const char *buoyShapes[] = {"Sphere", "Box"};
ImGui::Combo("Add Shape", &shapeIndex, buoyShapes, 2);

const Vec3 fluidCenter = world.water_fluid.beaker_center;
const float halfSize = 4.0f;
const float minX = fluidCenter.x - halfSize;
const float maxX = fluidCenter.x + halfSize;
const float minZ = fluidCenter.z - halfSize;
const float maxZ = fluidCenter.z + halfSize;

ImGui::DragFloat("X", &spawnPos[0], 0.1f);
ImGui::DragFloat("Y", &spawnPos[1], 0.1f);
ImGui::DragFloat("Z", &spawnPos[2], 0.1f);
spawnPos[0] = std::max(minX, std::min(maxX, spawnPos[0]));
spawnPos[2] = std::max(minZ, std::min(maxZ, spawnPos[2]));

ImGui::DragFloat("Density", &spawnDensity, 0.05f, 0.01f, 100000.0f);
const float prevVolume = spawnVolume;
ImGui::DragFloat("Volume", &spawnVolume, 0.01f, 0.0001f, 100.0f);
if (spawnVolume > 100.0f)
spawnVolume = prevVolume;

if (ImGui::Button("Add Body"))
{
static float last_add_time = -1000.0f;
float now = ImGui::GetTime();
if (now - last_add_time < 2.0f)
RequestEngineToast("Too frequent requests");
else
{
last_add_time = now;
Vec3 pos(spawnPos[0], spawnPos[1], spawnPos[2]);
if (std::abs(pos.x - fluidCenter.x) > halfSize || std::abs(pos.z - fluidCenter.z) > halfSize)
{
RequestEngineToast("Body spawn must be inside beaker X/Z.");
}
else
{
if (shapeIndex == 0)
sphereRadius = sphereRadiusFromVolume(spawnVolume);
else
{
const float h = std::cbrt(std::max(0.0f, spawnVolume) / 8.0f);
boxHalfSize[0] = boxHalfSize[1] = boxHalfSize[2] = h;
}
const float newRad = approx_radius_for_new_shape();
const auto &bodies = world.getBodies();
int overlap = 0;
for (auto &b : bodies)
{
if (!b.collider)
continue;
if (b.inverse_mass == 0.0f)
continue;
const float r = approx_radius_from_collider(b.collider);
const float dx = b.position.x - pos.x;
const float dy = b.position.y - pos.y;
const float dz = b.position.z - pos.z;
const float dist2 = dx * dx + dy * dy + dz * dz;
const float rsum = newRad + r;
const float thresh = rsum * 0.85f;
if (dist2 < thresh * thresh)
++overlap;
if (overlap >= 4)
break;
}
if (overlap >= 4)
RequestEngineToast("area too clustered to add a body");
else
{
spawn_body(world);
RequestEngineToast("Body was added successfully");
}
}
}
}
show_tooltip("Creates one rigid body with the current spawn parameters.");
return;
}

const bool restrictShapes = world.thermal_spawn_controls.lock_to_basic_shapes;
const char *shapeNamesFull[] = {"Sphere", "Box", "Ramp"};
const char *shapeNamesLimited[] = {"Sphere", "Box"};
Expand Down Expand Up @@ -270,6 +478,8 @@ void RenderAddBodyMenuContent(PhysicsWorld &world)
{
if (!b.collider)
continue;
if (world.enable_buoyancy && b.inverse_mass == 0.0f)
continue;
const float r = approx_radius_from_collider(b.collider);
const float dx = b.position.x - pos.x;
const float dy = b.position.y - pos.y;
Expand Down Expand Up @@ -416,6 +626,12 @@ void RenderBodyInspectorContent(PhysicsWorld &world, bool showCloseButton)
{
ImGui::PushID(body.id);

if (isBuoyancyHelperWall(world, body))
{
ImGui::PopID();
continue;
}

if (!body.collider)
{
ImGui::PopID();
Expand Down Expand Up @@ -452,13 +668,63 @@ void RenderBodyInspectorContent(PhysicsWorld &world, bool showCloseButton)

if (isSelected && isLive)
{
float editSpeed[3] = {body.velocity.x, body.velocity.y, body.velocity.z};
if (ImGui::DragFloat3("Edit Speed", editSpeed, 0.1f))
body.velocity = Vec3(editSpeed[0], editSpeed[1], editSpeed[2]);
if (world.enable_buoyancy)
{
if (body.collider->type == ShapeType::Sphere)
{
SphereCollider *sphere = static_cast<SphereCollider *>(body.collider);
const float currentVolume = sphereVolumeFromRadius(sphere->radius);
const float currentMass = (body.inverse_mass > 0.0f) ? (1.0f / body.inverse_mass) : 0.0f;
const float currentDensity = (currentVolume > 1e-6f) ? (currentMass / currentVolume) : 0.0f;

float editVolume = currentVolume;
float editDensity = currentDensity;
const float prevVolume = editVolume;
bool volChanged = ImGui::DragFloat("Volume", &editVolume, 0.01f, 0.0001f, 100.0f);
if (editVolume > 100.0f)
editVolume = prevVolume;
bool densChanged = ImGui::DragFloat("Density", &editDensity, 0.05f, 0.01f, 100000.0f);

if (volChanged || densChanged)
{
sphere->radius = sphereRadiusFromVolume(editVolume);
setBodyMassAndInertia(body, editDensity * editVolume);
}
}
else if (body.collider->type == ShapeType::Box)
{
BoxCollider *box = static_cast<BoxCollider *>(body.collider);
const Vec3 hs = box->halfsize;
const float currentVolume = (2.0f * hs.x) * (2.0f * hs.y) * (2.0f * hs.z);
const float currentMass = (body.inverse_mass > 0.0f) ? (1.0f / body.inverse_mass) : 0.0f;
const float currentDensity = (currentVolume > 1e-6f) ? (currentMass / currentVolume) : 0.0f;

float editVolume = currentVolume;
float editDensity = currentDensity;
const float prevVolume = editVolume;
bool volChanged = ImGui::DragFloat("Volume", &editVolume, 0.01f, 0.0001f, 100.0f);
if (editVolume > 100.0f)
editVolume = prevVolume;
bool densChanged = ImGui::DragFloat("Density", &editDensity, 0.05f, 0.01f, 100000.0f);

if (volChanged || densChanged)
{
const float scale = std::cbrt(std::max(0.0001f, editVolume) / std::max(1e-6f, currentVolume));
box->halfsize = Vec3(hs.x * scale, hs.y * scale, hs.z * scale);
setBodyMassAndInertia(body, editDensity * editVolume);
}
}
}
else
{
float editSpeed[3] = {body.velocity.x, body.velocity.y, body.velocity.z};
if (ImGui::DragFloat3("Edit Speed", editSpeed, 0.1f))
body.velocity = Vec3(editSpeed[0], editSpeed[1], editSpeed[2]);

float editForce[3] = {body.force_accum.x, body.force_accum.y, body.force_accum.z};
if (ImGui::DragFloat3("Edit Force", editForce, 0.1f))
body.force_accum = Vec3(editForce[0], editForce[1], editForce[2]);
float editForce[3] = {body.force_accum.x, body.force_accum.y, body.force_accum.z};
if (ImGui::DragFloat3("Edit Force", editForce, 0.1f))
body.force_accum = Vec3(editForce[0], editForce[1], editForce[2]);
}
if (body.thermal_enabled)
{
float editTemp = body.temperature;
Expand Down Expand Up @@ -497,7 +763,8 @@ void RenderBodyMenu(PhysicsWorld &world)
{
ImGui::Begin("Body Menu");
RenderAddBodyMenuContent(world);
RenderConstraintMenuContent(world);
if (!world.enable_buoyancy)
RenderConstraintMenuContent(world);
RenderWorldMenuContent(world);
RenderBodyInspectorContent(world, false);
ImGui::End();
Expand Down
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