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/*
Test case for collision/jerking issue.
*/
#include "test.h"
#include <vector>
#include <iostream>
class Skier : public Test
{
public:
Skier()
{
b2Body* ground = NULL;
{
b2BodyDef bd;
ground = m_world->CreateBody(&bd);
float const PlatformWidth = 8.0f;
/*
First angle is from the horizontal and should be negative for a downward slope.
Second angle is relative to the preceding slope, and should be positive, creating a kind of
loose 'Z'-shape from the 3 edges.
If A1 = -10, then A2 <= ~1.5 will result in the collision glitch.
If A1 = -30, then A2 <= ~10.0 will result in the glitch.
*/
float const Angle1Degrees = -30.0f;
float const Angle2Degrees = 10.0f;
/*
The larger the value of SlopeLength, the less likely the glitch will show up.
*/
float const SlopeLength = 2.0f;
float const SurfaceFriction = 0.2f;
// Convert to radians
float const Slope1Incline = -Angle1Degrees * b2_pi / 180.0f;
float const Slope2Incline = Slope1Incline - Angle2Degrees * b2_pi / 180.0f;
//
m_platform_width = PlatformWidth;
// Horizontal platform
b2Vec2 v1(-PlatformWidth, 0.0f);
b2Vec2 v2(0.0f, 0.0f);
b2Vec2 v3(SlopeLength * cosf(Slope1Incline), -SlopeLength * sinf(Slope1Incline));
b2Vec2 v4(v3.x + SlopeLength * cosf(Slope2Incline), v3.y - SlopeLength * sinf(Slope2Incline));
b2Vec2 v5(v4.x, v4.y - 1.0f);
b2Vec2 vertices[5] = { v5, v4, v3, v2, v1 };
b2ChainShape shape;
shape.CreateLoop(vertices, 5);
b2FixtureDef fd;
fd.shape = &shape;
fd.density = 0.0f;
fd.friction = SurfaceFriction;
ground->CreateFixture(&fd);
}
{
float const BodyWidth = 1.0f;
float const BodyHeight = 2.5f;
float const SkiLength = 3.0f;
/*
Larger values for this seem to alleviate the issue to some extent.
*/
float const SkiThickness = 0.3f;
float const SkiFriction = 0.0f;
float const SkiRestitution = 0.15f;
b2BodyDef bd;
bd.type = b2_dynamicBody;
float initial_y = BodyHeight / 2 + SkiThickness;
bd.position.Set(-m_platform_width / 2, initial_y);
b2Body* skier = m_world->CreateBody(&bd);
b2PolygonShape ski;
b2Vec2 verts[4];
verts[0].Set(-SkiLength / 2 - SkiThickness, -BodyHeight / 2);
verts[1].Set(-SkiLength / 2, -BodyHeight / 2 - SkiThickness);
verts[2].Set(SkiLength / 2, -BodyHeight / 2 - SkiThickness);
verts[3].Set(SkiLength / 2 + SkiThickness, -BodyHeight / 2);
ski.Set(verts, 4);
b2FixtureDef fd;
fd.density = 1.0f;
fd.friction = SkiFriction;
fd.restitution = SkiRestitution;
fd.shape = &ski;
skier->CreateFixture(&fd);
skier->SetLinearVelocity(b2Vec2(0.5f, 0.0f));
m_skier = skier;
}
g_camera.m_center = b2Vec2(m_platform_width / 2.0f, 0.0f);
g_camera.m_zoom = 0.4f;
m_fixed_camera = true;
}
void Keyboard(int key) override
{
switch (key)
{
case GLFW_KEY_C:
m_fixed_camera = !m_fixed_camera;
if(m_fixed_camera)
{
g_camera.m_center = b2Vec2(m_platform_width / 2.0f, 0.0f);
}
break;
}
}
void Step(Settings& settings) override
{
g_debugDraw.DrawString(5, m_textLine, "Keys: c = Camera fixed/tracking");
m_textLine += m_textIncrement;
if(!m_fixed_camera)
{
g_camera.m_center = m_skier->GetPosition();
}
Test::Step(settings);
}
static Test* Create()
{
return new Skier;
}
b2Body* m_skier;
float m_platform_width;
bool m_fixed_camera;
};
static int testIndex = RegisterTest("Bugs", "Skier", Skier::Create);
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