我需要在一个框架上画小圆圈,让它们在几帧后消失(淡出)。如何使用 OpenGL ES 实现这一点?
这是我到目前为止所拥有的,在框架中绘制圆圈的代码:
[EAGLContext setCurrentContext:context];
glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer);
glViewport(0, 0, backingWidth, backingHeight);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrthof(-1.0f, 1.0f, -1.5f, 1.5f, -1.0f, 1.0f);
glMatrixMode(GL_MODELVIEW);
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
GLfloat vertices[720];
for (int i = 0; i < 720; i += 2) {
vertices[i] = (cos(DEGREES_TO_RADIANS(i)) * 1);
vertices[i+1] = (sin(DEGREES_TO_RADIANS(i)) * 1);
}
glVertexPointer(2, GL_FLOAT, 0, vertices);
glEnableClientState(GL_VERTEX_ARRAY);
glColor4f(1.0f, 1.0f, 0.0f, 1.0f);
glDrawArrays(GL_TRIANGLE_FAN, 0, 360);
glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);
[context presentRenderbuffer:GL_RENDERBUFFER_OES];
我不明白的是如何跟踪同一个圆圈并在连续的帧中淡化它。谢谢