From f8e2028ac565fab120aef5039d2e97ee7af07202 Mon Sep 17 00:00:00 2001 From: Javidx9 <25419386+OneLoneCoder@users.noreply.github.com> Date: Mon, 3 Sep 2018 23:33:55 +0100 Subject: [PATCH] Testing Balls --- OneLoneCoder_PGE_Balls2.cpp | 457 ++++++++++++++++++++++++++++++++++++ 1 file changed, 457 insertions(+) create mode 100644 OneLoneCoder_PGE_Balls2.cpp diff --git a/OneLoneCoder_PGE_Balls2.cpp b/OneLoneCoder_PGE_Balls2.cpp new file mode 100644 index 0000000..8d6bf4a --- /dev/null +++ b/OneLoneCoder_PGE_Balls2.cpp @@ -0,0 +1,457 @@ +/* +OneLoneCoder.com - Programming Balls! #2 Circle Vs Edge Collisions +"...totally overkill for pong..." - @Javidx9 + +Disclaimer +~~~~~~~~~~ +I don't care what you use this for. It's intended to be educational, and perhaps +to the oddly minded - a little bit of fun. Please hack this, change it and use it +in any way you see fit. BUT, you acknowledge that I am not responsible for anything +bad that happens as a result of your actions. However, if good stuff happens, I +would appreciate a shout out, or at least give the blog some publicity for me. +Cheers! + +Background +~~~~~~~~~~ +Collision detection engines can get quite complicated. This program shows the interactions +between circular objects of different sizes and masses. Use Left mouse button to select +and drag a ball to examin static collisions, and use Right mouse button to apply velocity +to the balls as if using a pool/snooker/billiards cue. + +Author +~~~~~~ +Twitter: @javidx9 +Blog: www.onelonecoder.com +Twitch: https://www.twitch.tv/javidx9 +Discord: https://discord.gg/WhwHUMV + +Video: +~~~~~~ +Part #1 https://youtu.be/LPzyNOHY3A4 +Part #2 https://youtu.be/ebq7L2Wtbl4 + +Last Updated: 18/02/2017 +*/ + +#include +#include +using namespace std; + +#include "olcPixelGameEngine.h" + +struct sBall +{ + float px, py; + float vx, vy; + float ax, ay; + float ox, oy; + float radius; + float mass; + float friction; + int score; + int id; + float fSimTimeRemaining; + olc::Pixel col; +}; + +struct sLineSegment +{ + float sx, sy; + float ex, ey; + float radius; +}; + + + +class CirclePhysics : public olc::PixelGameEngine +{ +public: + CirclePhysics() + { + sAppName = "Circles V Edges"; + } + +private: + vector vecBalls; + vector vecLines; + vector> modelCircle; + sBall* pSelectedBall = nullptr; + olc::Sprite *spriteBalls = nullptr; + sLineSegment* pSelectedLine = nullptr; + bool bSelectedLineStart = false; + + void AddBall(float x, float y, float r = 5.0f, int s = 0) + { + sBall b; + b.px = x; b.py = y; + b.vx = 0; b.vy = 0; + b.ax = 0; b.ay = 0; + b.ox = 0; b.oy = 0; + b.radius = r; + b.mass = r * 10.0f; + b.friction = 0.0f; + b.score = s; + b.fSimTimeRemaining = 0.0f; + b.id = vecBalls.size(); + b.col = olc::Pixel(rand() % 200 + 55, rand() % 200 + 55, rand() % 200 + 55); + vecBalls.emplace_back(b); + } + +public: + bool OnUserCreate() + { + float fBallRadius = 4.0f; + for (int i = 0; i <300; i++) + AddBall(((float)rand()/(float)RAND_MAX) * ScreenWidth(), ((float)rand() / (float)RAND_MAX) * ScreenHeight(), fBallRadius); + + AddBall(28.0f, 33.0, fBallRadius * 3); + AddBall(28.0f, 35.0, fBallRadius * 2); + + float fLineRadius = 4.0f; + vecLines.push_back({ 12.0f, 4.0f, 64.0f, 4.0f, fLineRadius }); + vecLines.push_back({ 76.0f, 4.0f, 132.0f, 4.0f, fLineRadius }); + vecLines.push_back({ 12.0f, 68.0f, 64.0f, 68.0f, fLineRadius }); + vecLines.push_back({ 76.0f, 68.0f, 132.0f, 68.0f, fLineRadius }); + vecLines.push_back({ 4.0f, 12.0f, 4.0f, 60.0f, fLineRadius }); + vecLines.push_back({ 140.0f, 12.0f, 140.0f, 60.0f, fLineRadius }); + return true; + } + + bool OnUserUpdate(float fElapsedTime) + { + auto DoCirclesOverlap = [](float x1, float y1, float r1, float x2, float y2, float r2) + { + return fabs((x1 - x2)*(x1 - x2) + (y1 - y2)*(y1 - y2)) <= ((r1 + r2) * (r1 + r2)); + }; + + auto IsPointInCircle = [](float x1, float y1, float r1, float px, float py) + { + return fabs((x1 - px)*(x1 - px) + (y1 - py)*(y1 - py)) < (r1 * r1); + }; + + if (GetMouse(0).bPressed) + { + // Check for selected ball + pSelectedBall = nullptr; + for (auto &ball : vecBalls) + { + if (IsPointInCircle(ball.px, ball.py, ball.radius, GetMouseX(), GetMouseY())) + { + pSelectedBall = &ball; + break; + } + } + + // Check for selected line segment end + pSelectedLine = nullptr; + for (auto &line : vecLines) + { + if (IsPointInCircle(line.sx, line.sy, line.radius, GetMouseX(), GetMouseY())) + { + pSelectedLine = &line; + bSelectedLineStart = true; + break; + } + + if (IsPointInCircle(line.ex, line.ey, line.radius, GetMouseX(), GetMouseY())) + { + pSelectedLine = &line; + bSelectedLineStart = false; + break; + } + } + } + + if (GetMouse(0).bHeld) + { + if (pSelectedLine != nullptr) + { + if (bSelectedLineStart) + { + pSelectedLine->sx = GetMouseX(); + pSelectedLine->sy = GetMouseY(); + } + else + { + pSelectedLine->ex = GetMouseX(); + pSelectedLine->ey = GetMouseY(); + } + } + } + + if (GetMouse(0).bReleased) + { + if (pSelectedBall != nullptr) + { + // Apply velocity + pSelectedBall->vx = 5.0f * ((pSelectedBall->px) - GetMouseX()); + pSelectedBall->vy = 5.0f * ((pSelectedBall->py) - GetMouseY()); + } + + pSelectedBall = nullptr; + pSelectedLine = nullptr; + } + + if (GetMouse(1).bHeld) + { + for (auto &ball : vecBalls) + { + ball.vx += (GetMouseX() - ball.px) * 0.01f; + ball.vy += (GetMouseY() - ball.py) * 0.01f; + } + } + + + + vector> vecCollidingPairs; + vector vecFakeBalls; + + // Threshold indicating stability of object + float fStable = 0.005f; + + // Multiple simulation updates with small time steps permit more accurate physics + // and realistic results at the expense of CPU time of course + int nSimulationUpdates = 4; + + // Multiple collision trees require more steps to resolve. Normally we would + // continue simulation until the object has no simulation time left for this + // epoch, however this is risky as the system may never find stability, so we + // can clamp it here + int nMaxSimulationSteps = 15; + + // Break up the frame elapsed time into smaller deltas for each simulation update + float fSimElapsedTime = fElapsedTime / (float)nSimulationUpdates; + + // Main simulation loop + for (int i = 0; i < nSimulationUpdates; i++) + { + // Set all balls time to maximum for this epoch + for (auto &ball : vecBalls) + ball.fSimTimeRemaining = fSimElapsedTime; + + // Erode simulation time on a per objec tbasis, depending upon what happens + // to it during its journey through this epoch + for (int j = 0; j < nMaxSimulationSteps; j++) + { + // Update Ball Positions + for (auto &ball : vecBalls) + { + if (ball.fSimTimeRemaining > 0.0f) + { + ball.ox = ball.px; // Store original position this epoch + ball.oy = ball.py; + + ball.ax = -ball.vx * 0.8f; // Apply drag and gravity + ball.ay = -ball.vy * 0.8f + 100.0f; + + ball.vx += ball.ax * ball.fSimTimeRemaining; // Update Velocity + ball.vy += ball.ay * ball.fSimTimeRemaining; + + ball.px += ball.vx * ball.fSimTimeRemaining; // Update position + ball.py += ball.vy * ball.fSimTimeRemaining; + + // Crudely wrap balls to screen - note this cause issues when collisions occur on screen boundaries + if (ball.px < 0) ball.px += (float)ScreenWidth(); + if (ball.px >= ScreenWidth()) ball.px -= (float)ScreenWidth(); + if (ball.py < 0) ball.py += (float)ScreenHeight(); + if (ball.py >= ScreenHeight()) ball.py -= (float)ScreenHeight(); + + // Stop ball when velocity is neglible + if (fabs(ball.vx*ball.vx + ball.vy*ball.vy) < fStable) + { + ball.vx = 0; + ball.vy = 0; + } + } + } + + + // Work out static collisions with walls and displace balls so no overlaps + for (auto &ball : vecBalls) + { + float fDeltaTime = ball.fSimTimeRemaining; + + // Against Edges + for (auto &edge : vecLines) + { + // Check that line formed by velocity vector, intersects with line segment + float fLineX1 = edge.ex - edge.sx; + float fLineY1 = edge.ey - edge.sy; + + float fLineX2 = ball.px - edge.sx; + float fLineY2 = ball.py - edge.sy; + + float fEdgeLength = fLineX1 * fLineX1 + fLineY1 * fLineY1; + + // This is nifty - It uses the DP of the line segment vs the line to the object, to work out + // how much of the segment is in the "shadow" of the object vector. The min and max clamp + // this to lie between 0 and the line segment length, which is then normalised. We can + // use this to calculate the closest point on the line segment + float t = max(0, min(fEdgeLength, (fLineX1 * fLineX2 + fLineY1 * fLineY2))) / fEdgeLength; + + // Which we do here + float fClosestPointX = edge.sx + t * fLineX1; + float fClosestPointY = edge.sy + t * fLineY1; + + // And once we know the closest point, we can check if the ball has collided with the segment in the + // same way we check if two balls have collided + float fDistance = sqrtf((ball.px - fClosestPointX)*(ball.px - fClosestPointX) + (ball.py - fClosestPointY)*(ball.py - fClosestPointY)); + + if (fDistance <= (ball.radius + edge.radius)) + { + // Collision has occurred - treat collision point as a ball that cannot move. To make this + // compatible with the dynamic resolution code below, we add a fake ball with an infinite mass + // so it behaves like a solid object when the momentum calculations are performed + sBall *fakeball = new sBall(); + fakeball->radius = edge.radius; + fakeball->mass = ball.mass * 0.8f; + fakeball->px = fClosestPointX; + fakeball->py = fClosestPointY; + fakeball->vx = -ball.vx; // We will use these later to allow the lines to impart energy into ball + fakeball->vy = -ball.vy; // if the lines are moving, i.e. like pinball flippers + + // Store Fake Ball + vecFakeBalls.push_back(fakeball); + + // Add collision to vector of collisions for dynamic resolution + vecCollidingPairs.push_back({ &ball, fakeball }); + + // Calculate displacement required + float fOverlap = 1.0f * (fDistance - ball.radius - fakeball->radius); + + // Displace Current Ball away from collision + ball.px -= fOverlap * (ball.px - fakeball->px) / fDistance; + ball.py -= fOverlap * (ball.py - fakeball->py) / fDistance; + } + } + + // Against other balls + for (auto &target : vecBalls) + { + if (ball.id != target.id) // Do not check against self + { + if (DoCirclesOverlap(ball.px, ball.py, ball.radius, target.px, target.py, target.radius)) + { + // Collision has occured + vecCollidingPairs.push_back({ &ball, &target }); + + // Distance between ball centers + float fDistance = sqrtf((ball.px - target.px)*(ball.px - target.px) + (ball.py - target.py)*(ball.py - target.py)); + + // Calculate displacement required + float fOverlap = 0.5f * (fDistance - ball.radius - target.radius); + + // Displace Current Ball away from collision + ball.px -= fOverlap * (ball.px - target.px) / fDistance; + ball.py -= fOverlap * (ball.py - target.py) / fDistance; + + // Displace Target Ball away from collision - Note, this should affect the timing of the target ball + // and it does, but this is absorbed by the target ball calculating its own time delta later on + target.px += fOverlap * (ball.px - target.px) / fDistance; + target.py += fOverlap * (ball.py - target.py) / fDistance; + } + } + } + + // Time displacement - we knew the velocity of the ball, so we can estimate the distance it should have covered + // however due to collisions it could not do the full distance, so we look at the actual distance to the collision + // point and calculate how much time that journey would have taken using the speed of the object. Therefore + // we can now work out how much time remains in that timestep. + float fIntendedSpeed = sqrtf(ball.vx * ball.vx + ball.vy * ball.vy); + float fIntendedDistance = fIntendedSpeed * ball.fSimTimeRemaining; + float fActualDistance = sqrtf((ball.px - ball.ox)*(ball.px - ball.ox) + (ball.py - ball.oy)*(ball.py - ball.oy)); + float fActualTime = fActualDistance / fIntendedSpeed; + + // After static resolution, there may be some time still left for this epoch, so allow simulation to continue + ball.fSimTimeRemaining = ball.fSimTimeRemaining - fActualTime; + } + + // Now work out dynamic collisions + float fEfficiency = 1.00f; + for (auto c : vecCollidingPairs) + { + sBall *b1 = c.first, *b2 = c.second; + + // Distance between balls + float fDistance = sqrtf((b1->px - b2->px)*(b1->px - b2->px) + (b1->py - b2->py)*(b1->py - b2->py)); + + // Normal + float nx = (b2->px - b1->px) / fDistance; + float ny = (b2->py - b1->py) / fDistance; + + // Tangent + float tx = -ny; + float ty = nx; + + // Dot Product Tangent + float dpTan1 = b1->vx * tx + b1->vy * ty; + float dpTan2 = b2->vx * tx + b2->vy * ty; + + // Dot Product Normal + float dpNorm1 = b1->vx * nx + b1->vy * ny; + float dpNorm2 = b2->vx * nx + b2->vy * ny; + + // Conservation of momentum in 1D + float m1 = fEfficiency * (dpNorm1 * (b1->mass - b2->mass) + 2.0f * b2->mass * dpNorm2) / (b1->mass + b2->mass); + float m2 = fEfficiency * (dpNorm2 * (b2->mass - b1->mass) + 2.0f * b1->mass * dpNorm1) / (b1->mass + b2->mass); + + // Update ball velocities + b1->vx = tx * dpTan1 + nx * m1; + b1->vy = ty * dpTan1 + ny * m1; + b2->vx = tx * dpTan2 + nx * m2; + b2->vy = ty * dpTan2 + ny * m2; + } + + // Remove collisions + vecCollidingPairs.clear(); + + // Remove fake balls + for (auto &b : vecFakeBalls) delete b; + vecFakeBalls.clear(); + } + } + + // Clear Screen + FillRect(0, 0, ScreenWidth(), ScreenHeight(), olc::Pixel(0, 0, 0)); + + // Draw Lines + for (auto line : vecLines) + { + FillCircle(line.sx, line.sy, line.radius, olc::Pixel(255,255,255)); + FillCircle(line.ex, line.ey, line.radius, olc::Pixel(128, 128, 128)); + + float nx = -(line.ey - line.sy); + float ny = (line.ex - line.sx); + float d = sqrt(nx*nx + ny * ny); + nx /= d; + ny /= d; + + DrawLine((line.sx + nx * line.radius), (line.sy + ny * line.radius), (line.ex + nx * line.radius), (line.ey + ny * line.radius), olc::Pixel(255, 255, 255)); + DrawLine((line.sx - nx * line.radius), (line.sy - ny * line.radius), (line.ex - nx * line.radius), (line.ey - ny * line.radius), olc::Pixel(255, 255, 255)); + } + + // Draw Balls + for (auto ball : vecBalls) + FillCircle(ball.px, ball.py, ball.radius, ball.col); + + // Draw Cue + if (pSelectedBall != nullptr) + DrawLine(pSelectedBall->px, pSelectedBall->py, GetMouseX(), GetMouseY(), olc::Pixel(0, 0, 255)); + + return true; + } + +}; + + +int main() +{ + CirclePhysics game; + if (game.Construct(640, 480, 2, 2)) + game.Start(); + else + wcout << L"Could not construct console" << endl; + + return 0; +}; +