C++ 在OpenGL中使用多边形绘制二维粗弧
我想用多边形画一个粗弧(类似于模拟表盘的彩色部分)。为此,我在多边形中添加了顶点,它在外周长上运行良好,但在内周长(凹面)上连接端点 如果我将这些顶点添加到直线中,同样的逻辑也可以正常工作,但这会创建一个空/非填充弧 我添加顶点的逻辑是:C++ 在OpenGL中使用多边形绘制二维粗弧,c++,opengl,polygon,shapes,C++,Opengl,Polygon,Shapes,我想用多边形画一个粗弧(类似于模拟表盘的彩色部分)。为此,我在多边形中添加了顶点,它在外周长上运行良好,但在内周长(凹面)上连接端点 如果我将这些顶点添加到直线中,同样的逻辑也可以正常工作,但这会创建一个空/非填充弧 我添加顶点的逻辑是: for( float i = m_segmentVertex.size() - 1; i < vCount; i++ ) { float x1 = (m_segmentVertex[ i ].x ) * c
for( float i = m_segmentVertex.size() - 1; i < vCount; i++ )
{
float x1 = (m_segmentVertex[ i ].x ) * cosA - m_segmentVertex[ i ].y * sinA;
float y1 = (m_segmentVertex[ i ].x ) * sinA + m_segmentVertex[ i ].y * cosA;
addVertex( vec3( x1, y1, 0.0f ) );
}
for(float i=m_segmentVertex.size()-1;i
试着用一个三角形扇子,把你的刻度盘的中心作为第一个点。
可能添加顶点(vec3(0.0f,0.0f,0.0f));在你的循环之前
我还建议将I设为int或unsigned int,这里的浮点没有意义。请注意,
GL\u POLYGON
仅适用于凸多边形
您必须对凹多边形进行三角剖分。这是我通过三角剖分动态创建多边形的方法:
//create thick colored segments
void CreateArcMesh( float sAngle, float eAngle, vec4 color, int thickness, int radius )
{
ObjectMeshDynamic meshObj = new ObjectMeshDynamic();
vec3 vertex[0];
float dAngle = ( ( eAngle - sAngle ) / ( VERTEX_COUNT / 2.0f ) );
float cosA = cos( DEG2RAD * dAngle );
float sinA = sin( DEG2RAD * dAngle );
meshObj.setMaterial( "material_base", "*" );
meshObj.setProperty( "surface_base", "*" );
meshObj.setMaterialParameter( "diffuse_color", color, 0 );
//Add the material on both side as the indices for Triangle strip start from last vertex added
Material material = meshObj.getMaterialInherit(0);
material.setTwoSided( 1 );
meshObj.addTriangleStrip( VERTEX_COUNT + 2 );
vec3 startPos = vec3( radius * cos( DEG2RAD * sAngle ), radius * sin( DEG2RAD * sAngle ), 0.0f );
vertex.append( startPos );
vec3 secondPos = vec3( ( radius - thickness ) * cos( DEG2RAD * sAngle ), ( radius - thickness ) * sin( DEG2RAD * sAngle ), 0.0f );
vertex.append( secondPos );
float x1 = startPos.x * cosA - startPos.y * sinA;
float y1 = startPos.x * sinA + startPos.y * cosA;
vertex.append( vec3( x1, y1, 0.0f ) );
x1 = secondPos.x * cosA - secondPos.y * sinA;
y1 = secondPos.x * sinA + secondPos.y * cosA;
vertex.append( vec3( x1, y1, 0.0f ) );
forloop( int k = 0 ; VERTEX_COUNT + 2 )
{
x1 = ( vertex[ vertex.size() - 2 ].x ) * cosA - vertex[ vertex.size() - 2 ].y * sinA;
y1 = ( vertex[ vertex.size() - 2 ].x ) * sinA + vertex[ vertex.size() - 2 ].y * cosA;
vertex.append( vec3( x1, y1, 0.0f ) );
meshObj.addVertex( vertex[k] );
}
vertex.clear();
meshObj.updateBounds();
meshObj.flush();
}
对于不相交的凹多边形也是如此。因为在我的例子中,顶点不相交(我按顺序添加它们)