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#include "../../../shared_cpp/Renderer2d.h"
#include "../../../shared_cpp/types.h"
#include "../../../shared_cpp/mathlib.h"
struct PointMassUpdateData {
int32 index = 0;
Vector2 restingPosition; // Position is in world coordinates
Vector2 currentPosition; // Position is in world coordinates
Vector2 velocity;
Vector2 force;
bool isHovered = false;
PointMassUpdateData* neighbors[4];
};
EM_BOOL onMouseMove(int eventType, const EmscriptenMouseEvent *mouseEvent, void *userData);
EM_BOOL onMouseDown(int eventType, const EmscriptenMouseEvent *mouseEvent, void *userData);
EM_BOOL onMouseUp(int eventType, const EmscriptenMouseEvent *mouseEvent, void *userData);
struct SoftbodyRectangle {
// User defined
float32 width = 200;
float32 height = 200;
int32 springDensity = 10;
float32 k = 3.f; // in N /m
float32 c = 3.f;
float32 jointMassKg = 1.f;
// Calculated before runtime
Vector2 springDimensions;
// Runtime data
float32 totalTimeSeconds = 0.f;
PointMassUpdateData* updateData = NULL;
bool hasLastPositionChanged = false;
Vector2 lastMousePosition;
PointMassUpdateData* draggedVertex = NULL;
// Render data
Mesh2d mesh;
Mesh2d pointsMesh;
Vertex2d* vertices = NULL;
Vertex2d* pointsVertices = NULL;
void load(Renderer2d* renderer) {
Vector2 position = Vector2(800 / 2 - width / 2, 600 / 2 - height / 2);
springDimensions = Vector2(width / springDensity, height / springDensity);
int32 numVertices = springDensity * springDensity; // Each subdivision is a square.
int32 numIndices = 6 * ((springDensity - 1) * (springDensity - 1));
vertices = new Vertex2d[numVertices];
updateData = new PointMassUpdateData[numVertices];
auto indices = new GLuint[numIndices];
// Load a square with the desired density
int32 vIdx = 0;
int32 iIdx = 0;
float32 inverseDensity = 1.f / springDensity;
float32 halfInv = inverseDensity / 2.f;
for (int32 y = 0; y < springDensity; y++) { // Rows
for (int32 x = 0; x < springDensity; x++) { // Columns
Vector2 vpos = Vector2(x * inverseDensity - halfInv, y * inverseDensity- halfInv);
vpos.x = vpos.x * width + position.x;
vpos.y = vpos.y * height + position.y;
vertices[vIdx] = { vpos, Vector4(1, 0, 0, 1) };
updateData[vIdx].index = vIdx;
updateData[vIdx].restingPosition = vpos;
updateData[vIdx].currentPosition = vpos;
updateData[vIdx].force = Vector2(0, 0);
updateData[vIdx].velocity = Vector2(0, 0);
if (x != 0) updateData[vIdx].neighbors[0] = &updateData[vIdx - 1]; // Left
else updateData[vIdx].neighbors[0] = NULL;
if (x != springDensity - 1) updateData[vIdx].neighbors[1] = &updateData[vIdx + 1]; // Right
else updateData[vIdx].neighbors[1] = NULL;
if (y != 0) updateData[vIdx].neighbors[2] = &updateData[vIdx - springDensity]; // Top
else updateData[vIdx].neighbors[2] = NULL;
if (y != springDensity - 1) updateData[vIdx].neighbors[3] = &updateData[vIdx + springDensity]; // Bottom
else updateData[vIdx].neighbors[3] = NULL;
if (y != springDensity - 1 && x != springDensity - 1) {
indices[iIdx++] = vIdx;
indices[iIdx++] = vIdx + 1;
indices[iIdx++] = vIdx + springDensity;
indices[iIdx++] = vIdx + springDensity;
indices[iIdx++] = vIdx + springDensity + 1;
indices[iIdx++] = vIdx + 1;
}
vIdx++;
}
}
mesh.load(vertices, numVertices, indices, numIndices, renderer, GL_DYNAMIC_DRAW);
pointsVertices = new Vertex2d[numVertices];
for (int32 v = 0; v < numVertices; v++) {
pointsVertices[v].position = vertices[v].position;
pointsVertices[v].color = Vector4(0, 0, 0, 1);
}
pointsMesh.load(pointsVertices, numVertices, renderer, GL_DYNAMIC_DRAW);
delete [] indices;
// Setup callbacks
emscripten_set_mousemove_callback("#gl_canvas", this, false, onMouseMove);
emscripten_set_mousedown_callback("#gl_canvas", this, false, onMouseDown);
emscripten_set_mouseup_callback("#gl_canvas", this, false, onMouseUp);
}
Vector2 getForceBetweenPointMasses(PointMassUpdateData* first, PointMassUpdateData* second) {
auto relativeVelocity = second->velocity - first->velocity;
auto restLength = (first->restingPosition - second->restingPosition).length();
auto relativePosition = second->currentPosition - first->currentPosition;
auto currentLength = relativePosition.length();
auto positionDir = relativePosition.normalize();
auto dotProduct = positionDir.dot(relativeVelocity);
float32 springForce = k * (currentLength - restLength);
float32 dampingForce = c * dotProduct;
float32 totalForce = springForce + dampingForce;
return positionDir * totalForce;
}
void update(float32 dtSeconds) {
totalTimeSeconds += dtSeconds;
for (int32 v = 0; v < pointsMesh.numVertices; v++) {
auto pointMass = &updateData[v];
if (draggedVertex != NULL) {
if (pointMass == draggedVertex && hasLastPositionChanged) {
hasLastPositionChanged = false;
Vector2 displacement = lastMousePosition - pointMass->restingPosition;
// We need to limit the new position based off of the triangle
if (displacement.x > springDimensions.x) {
displacement.x = springDimensions.x;
}
else if (displacement.x < -springDimensions.x) {
displacement.x = -springDimensions.x;
}
if (displacement.y > springDimensions.y) {
displacement.y = springDimensions.y;
}
else if (displacement.y < -springDimensions.y) {
displacement.y = -springDimensions.y;
}
pointMass->currentPosition = pointMass->restingPosition + displacement;
vertices[v].position = pointMass->currentPosition;
pointsVertices[v].position = pointMass->currentPosition;
}
}
else {
// Add the forces from it's neighbors
for (int32 n = 0; n < 4; n++) {
auto neighbor = pointMass->neighbors[n];
if (neighbor == NULL) continue;
pointMass->force += getForceBetweenPointMasses(pointMass, neighbor);
}
pointMass->velocity = pointMass->velocity + (pointMass->force / jointMassKg) * dtSeconds;
pointMass->currentPosition = pointMass->currentPosition + (pointMass->velocity * dtSeconds);
const float32 COLLISION_DISTANCE = 4.f;
for (int32 n = 0; n < pointsMesh.numVertices; n++) {
if (n == v) continue;
auto neighbor = &updateData[n];
if ((neighbor->currentPosition - pointMass->currentPosition).length() < COLLISION_DISTANCE) {
auto positionNormal = (neighbor->currentPosition - pointMass->currentPosition).normalize();
pointMass->currentPosition = neighbor->currentPosition - positionNormal * COLLISION_DISTANCE;
float32 dotProduct = pointMass->velocity.dot(positionNormal);
pointMass->velocity = pointMass->velocity - positionNormal * (2 * dotProduct);
}
}
vertices[v].position = pointMass->currentPosition;
pointsVertices[v].position = pointMass->currentPosition;
// Hovering highlights behavior
if (hasLastPositionChanged) {
if ((pointMass->currentPosition - lastMousePosition).length() < 10.f) {
pointsVertices[v].color = Vector4(1, 1, 0, 1);
pointMass->isHovered = true;
for (int32 n = 0; n < 4; n++) {
if (pointMass->neighbors[n])
pointsVertices[pointMass->neighbors[n]->index].color = Vector4(0, 0, 1, 1);
}
}
else if (pointMass->isHovered) {
pointsVertices[v].color = Vector4(0, 0, 0, 1);
for (int32 n = 0; n < 4; n++) {
if (pointMass->neighbors[n] && !pointMass->neighbors[n]->isHovered)
pointsVertices[pointMass->neighbors[n]->index].color = Vector4(0, 0, 0, 1);
}
pointMass->isHovered = false;
}
}
}
}
if (hasLastPositionChanged) hasLastPositionChanged = false;
mesh.updateVertices(vertices);
pointsMesh.updateVertices(pointsVertices);
}
void render(Renderer2d* renderer) {
mesh.render(renderer);
pointsMesh.render(renderer, GL_POINTS);
}
void unload() {
mesh.unload();
pointsMesh.unload();
delete [] vertices;
delete [] pointsVertices;
}
};
EM_BOOL onMouseMove(int eventType, const EmscriptenMouseEvent *mouseEvent, void *userData) {
SoftbodyRectangle* rectangle = (SoftbodyRectangle*)userData;
rectangle->hasLastPositionChanged = true;
rectangle->lastMousePosition = Vector2(static_cast<float32>(mouseEvent->targetX), static_cast<float32>(600 - mouseEvent->targetY));
return true;
}
EM_BOOL onMouseDown(int eventType, const EmscriptenMouseEvent *mouseEvent, void *userData) {
SoftbodyRectangle* rectangle = (SoftbodyRectangle*)userData;
for (int32 v = 0; v < rectangle->pointsMesh.numVertices; v++) {
auto pointMass = &rectangle->updateData[v];
if (pointMass->isHovered) {
rectangle->draggedVertex = pointMass;
break;
}
}
return true;
}
EM_BOOL onMouseUp(int eventType, const EmscriptenMouseEvent *mouseEvent, void *userData) {
SoftbodyRectangle* rectangle = (SoftbodyRectangle*)userData;
rectangle->draggedVertex = NULL;
return true;
}
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