【发布时间】：2019-12-23 06:32:21
【问题描述】：
我可以斜切矩形的角。
当我拉伸矩形而不是尝试倾斜它时，结果看起来并不平滑，它应该看起来像右侧的矩形。
当矩形被拉伸时如何计算三角形扇形的点？
目前这是我计算四分之一圆点的方式。
std::vector<float> bevelData;
bevelData.push_back(0.0); // First set the centre of the rectangle to the data
bevelData.push_back(0.0);
bevelData.push_back(0.0);
bevelData.push_back(0);
bevelData.push_back(0);
bevelData.push_back(1);
bevelData.push_back(0);
bevelData.push_back(0);
for (int i = 0; i <= segments; ++i) {
float x, y;
float angle = start_angle + 0.5 * M_PI * i / static_cast<float>(segments);
x = circX + cos(angle) * rad; // circX is the centre of the circle as marked in yellow in the first image
y = circY + sin(angle) * rad; // circY is the centre of the circle as marked in yellow in the first image , rad is the radius of the circle
bevelData.push_back(x);
bevelData.push_back(y);
bevelData.push_back(0.0);
bevelData.push_back(0);
bevelData.push_back(0);
bevelData.push_back(1);
bevelData.push_back(0);
bevelData.push_back(0);
}
//Bevel Bottom Right
float rightWidthBottom = (width / 2) - rightBottomBevel;
float rightHeightBottom = (height / 2) - rightBottomBevel;
std::vector<float> bottomRightBevelData = draw_bevel(rightWidthBottom, rightHeightBottom, rightBottomBevel, 1, -1, iSegmentsRightBottom);
std::vector<float> SuperRectangle::draw_bevel(float p_x, float p_y, float rad, int dir_x, int dir_y , int segments)
{
std::vector<float> bevelData;
float c_x, c_y; // the center of the circle
float start_angle; // the angle where to start the arc
bevelData.push_back(0.0);
bevelData.push_back(0.0);
bevelData.push_back(0.0);
bevelData.push_back(0);
bevelData.push_back(0);
bevelData.push_back(1);
bevelData.push_back(0);
bevelData.push_back(0);
c_x = p_x * dir_x;
c_y = p_y * dir_y;
if (dir_x == 1 && dir_y == 1)
start_angle = 0.0;
else if (dir_x == 1 && dir_y == -1)
start_angle = -M_PI * 0.5f;
else if (dir_x == -1 && dir_y == 1)
start_angle = M_PI * 0.5f;
else if (dir_x == -1 && dir_y == -1)
start_angle = M_PI;
for (int i = 0; i <= segments; ++i) {
float x, y;
float angle = start_angle + 0.5 * M_PI * i / static_cast<float>(segments);
x = c_x + cos(angle) * rad;
y = c_y + sin(angle) * rad;
float fscale = (y / (float)(height / 2.0f));
x = (x + (strech * fscale));
bevelData.push_back(x);
bevelData.push_back(y);
bevelData.push_back(0.0);
bevelData.push_back(0);
bevelData.push_back(0);
bevelData.push_back(1);
bevelData.push_back(0);
bevelData.push_back(0);
}
return bevelData;
}
/////////////////////////////////////// //////////////////
float xWidth = width / 2;
float yHeight = height / 2;
float TriangleRight[] = {
// positions // Normals // Texture Coord
0.0f , 0.0f , 0.0f , 0.0f,0.0,1.0, 0.0,0.0,
xWidth + strech , yHeight - rightTopBevel,0.0f, 0.0f,0.0,1.0 , 0.0,0.0,
xWidth - strech , -yHeight + rightBottomBevel,0.0f, 0.0f,0.0,1.0 , 0.0,0.0,
};
float TriangleLeft[] = {
// positions
0.0f , 0.0f , 0.0f , 0.0f,0.0,1.0, 0.0,0.0,
-xWidth + strech , yHeight - leftTopBevel ,0.0f, 0.0f,0.0,1.0 , 0.0,0.0,
-xWidth - strech , -yHeight + leftBottomBevel,0.0f, 0.0f,0.0,1.0 , 0.0,0.0,
};
float TriangleTop[] = {
// positions
0.0f , 0.0f , 0.0f , 0.0f,0.0,1.0, 0.0,0.0,
xWidth - rightTopBevel + strech , yHeight ,0.0f, 0.0f,0.0,1.0 , 0.0,0.0,
-xWidth + leftTopBevel + strech , yHeight,0.0f, 0.0f,0.0,1.0 , 0.0,0.0,
};
float TriangleBottom[] = {
// positions
0.0f , 0.0f , 0.0f , 0.0f,0.0,1.0, 0.0,0.0,
xWidth - rightBottomBevel - strech , -yHeight ,0.0f, 0.0f,0.0,1.0 , 0.0,0.0,
-xWidth + leftBottomBevel - strech , -yHeight,0.0f, 0.0f,0.0,1.0 , 0.0,0.0,
};
【问题讨论】：
-
您需要对顶点执行此操作吗？我和你有同样的问题，我的解决方案是制作一个矩形并给每个顶点一个法线并在片段着色器中计算它。它看起来也会更好，因为它将按片段而不是按顶点计算。
-
@Rhu Mage 是的，我需要对顶点执行此操作，因为我也会挤出此几何体。