实现了16种roundBox，见图
核心绘制码在RoundBox.h文件：
#ifndef ROUNDBOXRENDER_H
#define ROUNDBOXRENDER_H
struct RoundBoxRender
{
// 产生一个渐变的效果：
// shadetop叠加top
// shadedown叠加到down 可以为负
// rad为圆角的半径
/* linear horizontal shade within button or in outline */
/* view2d scrollers use it */
static void gl_round_box_shade(int mode, float minx, float miny, float maxx, float maxy, float rad, float shadetop, float shadedown)
{
float vec[7][2]= {{0.195, 0.02}, {0.383, 0.067}, {0.55, 0.169}, {0.707, 0.293},
{0.831, 0.45}, {0.924, 0.617}, {0.98, 0.805}};
float div= maxy-miny;
float coltop[3], coldown[3], color[4];
int a;
/* mult */
for(a=0; a<7; a++) {
vec[a][0]*= rad; vec[a][1]*= rad;
}
/* get current color, needs to be outside of glBegin/End */
glGetFloatv(GL_CURRENT_COLOR, color);
/* 'shade' defines strength of shading */
coltop[0]= color[0]+shadetop; if(coltop[0]>1.0) coltop[0]= 1.0;
coltop[1]= color[1]+shadetop; if(coltop[1]>1.0) coltop[1]= 1.0;
coltop[2]= color[2]+shadetop; if(coltop[2]>1.0) coltop[2]= 1.0;
coldown[0]= color[0]+shadedown; if(coldown[0]<0.0) coldown[0]= 0.0;
coldown[1]= color[1]+shadedown; if(coldown[1]<0.0) coldown[1]= 0.0;
coldown[2]= color[2]+shadedown; if(coldown[2]<0.0) coldown[2]= 0.0;
glShadeModel(GL_SMOOTH);
glBegin(mode);
/* start with corner right-bottom */
if(roundboxtype & 4) {
round_box_shade_col(coltop, coldown, 0.0);
glVertex2f(maxx-rad, miny);
for(a=0; a<7; a++) {
round_box_shade_col(coltop, coldown, vec[a][1]/div);
glVertex2f(maxx-rad+vec[a][0], miny+vec[a][1]);
}
round_box_shade_col(coltop, coldown, rad/div);
glVertex2f(maxx, miny+rad);
}
else {
round_box_shade_col(coltop, coldown, 0.0);
glVertex2f(maxx, miny);
}
/* corner right-top */
if(roundboxtype & 2) {
round_box_shade_col(coltop, coldown, (div-rad)/div);
glVertex2f(maxx, maxy-rad);
for(a=0; a<7; a++) {
round_box_shade_col(coltop, coldown, (div-rad+vec[a][1])/div);
glVertex2f(maxx-vec[a][1], maxy-rad+vec[a][0]);
}
round_box_shade_col(coltop, coldown, 1.0);
glVertex2f(maxx-rad, maxy);
}
else {
round_box_shade_col(coltop, coldown, 1.0);
glVertex2f(maxx, maxy);
}
/* corner left-top */
if(roundboxtype & 1) {
round_box_shade_col(coltop, coldown, 1.0);
glVertex2f(minx+rad, maxy);
for(a=0; a<7; a++) {
round_box_shade_col(coltop, coldown, (div-vec[a][1])/div);
glVertex2f(minx+rad-vec[a][0], maxy-vec[a][1]);
}
round_box_shade_col(coltop, coldown, (div-rad)/div);
glVertex2f(minx, maxy-rad);
}
else {
round_box_shade_col(coltop, coldown, 1.0);
glVertex2f(minx, maxy);
}
/* corner left-bottom */
if(roundboxtype & 8) {
round_box_shade_col(coltop, coldown, rad/div);
glVertex2f(minx, miny+rad);
for(a=0; a<7; a++) {
round_box_shade_col(coltop, coldown, (rad-vec[a][1])/div);
glVertex2f(minx+vec[a][1], miny+rad-vec[a][0]);
}
round_box_shade_col(coltop, coldown, 0.0);
glVertex2f(minx+rad, miny);
}
else {
round_box_shade_col(coltop, coldown, 0.0);
glVertex2f(minx, miny);
}
glEnd();
glShadeModel(GL_FLAT);
}
static void setType(int nType){
roundboxtype = nType % 16;
}
protected:
static void round_box_shade_col(float *col1, float *col2, float fac)
{
float col[3];
col[0]= (fac*col1[0] + (1.0-fac)*col2[0]);
col[1]= (fac*col1[1] + (1.0-fac)*col2[1]);
col[2]= (fac*col1[2] + (1.0-fac)*col2[2]);
glColor3fv(col);
}
static int roundboxtype;
};
int RoundBoxRender::roundboxtype = 3;
#endif
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