在OpenGL ES 1.1中用切出的扇形画一个圆 [英] Drawing a circle with a sector cut out in OpenGL ES 1.1

问题描述

我正在尝试使用OpenGL ES 1.1绘制以下形状.好吧，我被困住了，我真的不知道该怎么做.

I'm trying to draw the following shape using OpenGL ES 1.1. And well, I'm stuck, I don't really know how to go about it.

我的游戏当前使用的是Android的Canvas API，该API并未通过硬件加速，因此我将使用OpenGL ES对其进行重写. Canvas类具有一个名为drawArc的方法，该方法使绘制此形状变得非常容易.

My game currently uses Android's Canvas API, which isn't hardware accelerated, so I'm rewriting it with OpenGL ES. The Canvas class has a method called drawArc which makes drawing this shape very very easy; Canvas.drawArc

是否有关于使用OpenGL ES的建议/提示?

Any advice/hints on doing the same with OpenGL ES?

感谢您的阅读.

推荐答案

void gltDrawArc(unsigned int const segments, float angle_start, float angle_stop)
{
    int i;
    float const angle_step = (angle_stop - angle_start)/segments;

    GLfloat *arc_vertices;
    arc_vertices = malloc(2*sizeof(GLfloat) * (segments+2));

    arc_vertices[0] = arc_vertices[1] = 0.

    for(i=0; i<segments+1; i++) {
        arc_vertices[2 + 2*i    ] = cos(angle_start + i*angle_step);
        arc_vertices[2 + 2*i + 1] = sin(angle_start + i*angle_step);
    }
    glVertexPointer(2, GL_FLOAT, 0, arc_vertices);
    glEnableClientState(GL_VERTEX_ARRAY);
    glDrawArrays(GL_TRIANGLE_FAN, 0, segments+2);
    free(arc_vertices);
}

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