From db4bcc0073fa1042e9779453af1dcdef7582fbd1 Mon Sep 17 00:00:00 2001 From: Matthew Kosarek Date: Sun, 18 Apr 2021 15:10:25 -0400 Subject: Have 2D pill collisions working pretty well now --- frontend/2d/_collisions/pill_line/dist/output.wasm | Bin 59663 -> 58666 bytes frontend/2d/_collisions/pill_line/main.cpp | 73 +++++++++++---------- frontend/shared_cpp/WebglHelper.h | 6 ++ frontend/shared_cpp/mathlib.h | 7 ++ 4 files changed, 53 insertions(+), 33 deletions(-) create mode 100644 frontend/shared_cpp/WebglHelper.h diff --git a/frontend/2d/_collisions/pill_line/dist/output.wasm b/frontend/2d/_collisions/pill_line/dist/output.wasm index 89ef8ce..ddf862c 100755 Binary files a/frontend/2d/_collisions/pill_line/dist/output.wasm and b/frontend/2d/_collisions/pill_line/dist/output.wasm differ diff --git a/frontend/2d/_collisions/pill_line/main.cpp b/frontend/2d/_collisions/pill_line/main.cpp index 8700649..9f585f1 100644 --- a/frontend/2d/_collisions/pill_line/main.cpp +++ b/frontend/2d/_collisions/pill_line/main.cpp @@ -33,11 +33,13 @@ struct Rigidbody { force += f; } - void applyGravity() { - force += Vector2 { 0.f, -100.f }; + void applyGravity(float32 deltaTimeSeconds) { + velocity += (Vector2 { 0.f, -96.f } * deltaTimeSeconds); } void update(float32 deltaTimeSeconds) { + applyGravity(deltaTimeSeconds); + Vector2 acceleration = force / mass; velocity += (acceleration * deltaTimeSeconds); position += (velocity * deltaTimeSeconds); @@ -103,7 +105,7 @@ struct Pill { shape.load(vertices, numVertices, renderer); body.reset(); - // https://byjus.com/jee/moment-of-inertia-of-ellipse/ + body.mass = 100.f; body.momentOfInertia = (body.mass * (a * a + b * b)) / 4.f; a = width / 2.f; @@ -151,7 +153,7 @@ struct LineSegment { shape.load(vertices, 2, renderer); body.reset(); - body.mass = 100000.f; + body.mass = 1000000000.f; body.cofOfRestition = 1.f; body.rotationalVelocity = 0; body.velocity = Vector2(); @@ -172,6 +174,10 @@ struct LineSegment { start.y + (end.y - start.y) * t, }; } + + Vector2 getNormal() { + return (end - start).getPerp().normalize(); + } }; struct IntersectionResult { @@ -208,9 +214,8 @@ int main() { void load() { renderer.load(&context); - pill.body.position = Vector2 { context.width / 2.f, context.height / 2.f }; + pill.body.position = Vector2 { context.width / 4.f, context.height / 2.f }; pill.load(&renderer, 64, 100.f, 50.f); - pill.body.rotationalVelocity = 0.3f; segmentList[0].load(&renderer, Vector4().fromColor(191, 251, 146, 255.f), Vector2 { 50.f, 0.f }, Vector2 { 50.f, static_cast(context.height) }); segmentList[1].load(&renderer, Vector4().fromColor(159, 224, 210, 255.f), Vector2 { context.width - 50.f, 0.f }, Vector2 { context.width - 50.f, static_cast(context.height) }); @@ -220,11 +225,6 @@ void load() { mainLoop.run(update); } -float32 areaOfTriangle(Vector2 a, Vector2 b, Vector2 c) { - // Refernce for this for the formula: https://www.onlinemath4all.com/area-of-triangle-using-determinant-formula.html - return ABS(0.5 * (a.x * b.y - b.x * a.y + b.x * c.y - c.x * b.y + c.x * a.y - a.x * c.y)); -} - IntersectionResult getIntersection(Pill* pill, LineSegment* segment) { IntersectionResult result; Mat4x4 inverseModel = pill->shape.model.inverse(); @@ -241,22 +241,28 @@ IntersectionResult getIntersection(Pill* pill, LineSegment* segment) { return result; } - float32 t1 = (-B + sqrtf(determinant)) / (2 * A); - float32 t2 = (-B - sqrtf(determinant)) / (2 * A); + float32 t; + if (determinant < 0.001f) { + t = -B / (2.f * A); + } else { + t = (-B + sqrtf(determinant)) / (2.f * A); + // Or: t = (-B - sqrtf(determinant)) / (2 * A); + } + + Vector2 pointOnLine = segment->getPointOnLine(t); // This point is in world space and line space, since the line is in world space - Vector2 pointOnLine = segment->getPointOnLine(t1); // This point is in world space and line space, since the line is in world space - Vector2 pointOnEllipse = pointOnLine - pill->body.position; // This point is in ellipse space - pointOnEllipse.printDebug("Point on ellipse"); + Vector2 pointOnTransformedLine = { + start.x + (end.x - start.x) * t, + start.y + (end.y - start.y) * t + }; - float32 parametricTEllipse = atan2f( pointOnEllipse.y / pill->b , pointOnEllipse.x / pill->a ); - Vector2 tangent = { -pill->a * sinf(parametricTEllipse), pill->b * cosf(parametricTEllipse) }; - Vector2 normal = tangent.getPerp(); - normal.printDebug("Normal"); - // or: Vector2 normal = { pointOnEllipse.x * (pill->b / pill->a), pointOnEllipse.y * (pill->a / pill->b) }; + Vector2 pointOnEllipse = (pointOnTransformedLine); + + Vector2 normal = segment->getNormal(); result.intersect = true; - result.relativeVelocity = pill->body.velocity - segment->body.velocity;; - result.collisionNormal = normal.normalize(); + result.relativeVelocity = pill->body.velocity - segment->body.velocity; + result.collisionNormal = normal; result.firstPointOfApplication = pointOnEllipse; result.secondPointOfApplication = pointOnLine; @@ -270,24 +276,24 @@ void resolveCollision(Rigidbody* first, Rigidbody* second, IntersectionResult* i Vector2 secondPerp = ir->secondPointOfApplication.getPerp(); float32 cofOfRestition = (first->cofOfRestition + second->cofOfRestition) / 2.f; - float32 lNumerator = (relativeVelocity * -(1.0 + cofOfRestition)).dot(collisionNormal); - float32 lLinearDenomPart = collisionNormal.dot(collisionNormal * (1 / first->mass + 1 / second->mass)); - float32 lRotationalDenomPart = powf(firstPerp.dot(collisionNormal), 2) / first->momentOfInertia + powf(secondPerp.dot(collisionNormal), 2) / second->momentOfInertia; + float32 lNumerator = (relativeVelocity * -(1.f + cofOfRestition)).dot(collisionNormal); + float32 lLinearDenomPart = collisionNormal.dot(collisionNormal * (1.f / first->mass + 1.f / second->mass)); + float32 lRotationalDenomPart = powf(firstPerp.dot(collisionNormal), 2.f) / first->momentOfInertia + powf(secondPerp.dot(collisionNormal), 2) / second->momentOfInertia; + + //ir->firstPointOfApplication.printDebug("PoA"); + //firstPerp.printDebug("PoA Perp"); + //collisionNormal.printDebug("Normal"); + //printf("Dot: %f\n", firstPerp.dot(collisionNormal)); float32 lImpulseMagnitude = lNumerator / (lLinearDenomPart + lRotationalDenomPart); first->velocity = first->velocity + (collisionNormal * (lImpulseMagnitude / first->mass)); second->velocity = second->velocity - (collisionNormal * (lImpulseMagnitude / second->mass)); - first->rotationalVelocity = first->rotationalVelocity + firstPerp.dot(collisionNormal * lImpulseMagnitude) / first->momentOfInertia; second->rotationalVelocity = second->rotationalVelocity - secondPerp.dot(collisionNormal * lImpulseMagnitude) / second->momentOfInertia; } void update(float32 deltaTimeSeconds, void* userData) { - - // Input - pill.body.applyGravity(); - // Update Pill copyPill = pill.copy(); pill.update(deltaTimeSeconds); @@ -308,7 +314,7 @@ void update(float32 deltaTimeSeconds, void* userData) { pill.update(subdividedTimeSeconds); subIr = getIntersection(&pill, &segmentList[lineIdx]); - if (subdividedTimeSeconds == 0.f) { + if (subdividedTimeSeconds <= 0.f) { printf("Error: Should not be happening.\n"); break; } @@ -316,7 +322,8 @@ void update(float32 deltaTimeSeconds, void* userData) { printf("Found intersection at timestamp: %f\n", subdividedTimeSeconds); resolveCollision(&pill.body, &segmentList[lineIdx].body, &ir); - pill.update(deltaTimeSeconds - subdividedTimeSeconds); + deltaTimeSeconds = deltaTimeSeconds - subdividedTimeSeconds; + pill.update(deltaTimeSeconds); } } diff --git a/frontend/shared_cpp/WebglHelper.h b/frontend/shared_cpp/WebglHelper.h new file mode 100644 index 0000000..dbdb23f --- /dev/null +++ b/frontend/shared_cpp/WebglHelper.h @@ -0,0 +1,6 @@ +#pragma once +#include "mathlib.h" + +struct OrthographicRenderer; + +void render2DArrow(Vector2 start, Vector2 end, OrthographicRenderer* renderer); diff --git a/frontend/shared_cpp/mathlib.h b/frontend/shared_cpp/mathlib.h index 383c880..b9f3fee 100644 --- a/frontend/shared_cpp/mathlib.h +++ b/frontend/shared_cpp/mathlib.h @@ -57,6 +57,13 @@ struct Vector2 { return { -y, x }; } + Vector2 rotate(float angle) { + return { + x * cosf(angle) - y * sinf(angle), + x * sinf(angle) + y * cosf(angle) + }; + } + void printDebug(const char* name) { printf("%s=Vector2(%f, %f)\n", name, x, y); } -- cgit v1.2.1