Box2D:如何手动渲染实体 [英] Box2D: How to manually render a body
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问题描述
我成功将Box2D安装到我的项目中.但是我该如何渲染一个身体?假设我使用的东西支持绘制多边形.我只想找出身体多边形顶点的当前位置,并用引擎绘制它.
I succeed installing Box2D into my project. But how can I render a body? Assume I'm using something that supports drawing polygons. I just want to find out the current positions of the vertices of the body-polygon, to draw it with the engine.
如果您能帮助我,我将非常感激.
If you can help me, I will be very thankful.
推荐答案
我找到了!!!
void Box2DUtils::DrawBody(SDL_Surface *buffer, b2Body *body, int fr, int fg, int fb, int falpha, int lr, int lg, int lb, int lalpha, bool aa)
{
const b2Transform& xf = body->GetTransform();
for (b2Fixture* f = body->GetFixtureList(); f; f = f->GetNext())
{
switch (f->GetType())
{
case b2Shape::e_circle:
{
b2CircleShape* circle = (b2CircleShape*) f->GetShape();
b2Vec2 center = b2Mul(xf, circle->m_p);
float32 radius = circle->m_radius;
b2Vec2 axis = xf.R.col1;
//m_debugDraw->DrawSolidCircle(center, radius, axis, color);
if (falpha > 0)
{
filledCircleRGBA(buffer, center.x, center.y, (int) radius, fr, fg, fb, falpha);
}
if (lalpha > 0)
{
if (aa)
{
aacircleRGBA(buffer, center.x, center.y, (int) radius, lr, lg, lb, lalpha);
} else
{
aacircleRGBA(buffer, center.x, center.y, (int) radius, lr, lg, lb, lalpha);
}
} else if (aa)
{
aacircleRGBA(buffer, center.x, center.y, (int) radius, fr, fg, fb, falpha);
}
}
break;
case b2Shape::e_polygon:
{
b2PolygonShape* poly = (b2PolygonShape*) f->GetShape();
int32 vertexCount = poly->m_vertexCount;
b2Assert(vertexCount <= b2_maxPolygonVertices);
b2Vec2 vertices[b2_maxPolygonVertices];
Sint16 xv[b2_maxPolygonVertices];
Sint16 yv[b2_maxPolygonVertices];
for (int32 i = 0; i < vertexCount; ++i)
{
vertices[i] = b2Mul(xf, poly->m_vertices[i]);
xv[i] = (int) vertices[i].x;
yv[i] = (int) vertices[i].y;
}
if (falpha > 0)
{
filledPolygonRGBA(buffer, xv, yv, (Sint16) vertexCount, fr, fg, fb, falpha);
}
if (lalpha > 0)
{
if (aa)
{
aapolygonRGBA(buffer, xv, yv, (Sint16) vertexCount, lr, lg, lb, lalpha);
} else
{
polygonRGBA(buffer, xv, yv, (Sint16) vertexCount, lr, lg, lb, lalpha);
}
} else if (aa)
{
aapolygonRGBA(buffer, xv, yv, (Sint16) vertexCount, fr, fg, fb, falpha);
}
//m_debugDraw->DrawSolidPolygon(vertices, vertexCount, color);
}
break;
}
}
}
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