如何用OpenGL绘制光环效果？

Question

我正在点亮一个3D场景，我希望我可以代表光源（可能会改变方向，点和聚光灯）：

我试图绘制一个圆圈（使用vbo）并使用GL_BLEND，但不能正常工作，不会给出所需的结果。

指导我们如何产生这种效果。

代码（相关部分）：

void TemplateLight(){ //Light source with center in (0,0,0) and radius = 1
float angle, x, y, z = 0.f;
vertices[0] = vec3(0.f); 
GLuint vbo; 

for(int i=0; i<=divf; ++i){
    angle = (2*PI/(float)divf)*(float)i;
    x = vertices[0].x + cosf(angle);
    y = vertices[0].y + sinf(angle);

    vertices[i+1] = vec3(x,y,z);
}
glGenBuffers(1, &vbo); 
glGenVertexArrays(1, &vao);

glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);

glBindVertexArray(vao);
glEnableVertexAttribArray(attrib_vertex);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glVertexAttribPointer(attrib_vertex, 3, GL_FLOAT, GL_FALSE, 0, 0);

glBindVertexArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
}

mat4 ModelMatrix(){ //Moves drawing template to the current position of the light
return translate(mat4(1.f), vec3(position))*scale(mat4(1.f), vec3(0.05f,0.05f,1.f)); }

void Draw(){
    glBindVertexArray(vao);
    glDrawArrays(GL_TRIANGLE_FAN, 0, divf*3);
    glBindVertexArray(0);
}

void Display(){
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

glUseProgram(l_program[0].id);
l_program[0].SendUniformsMatricesToShader();
l_program[0].SendUniformsMaterialToShader(scene[0].material);
l_program[0].SendUniformsLightsToShader(ambient, ambient_info);
for(int i=0; i<MAX_LIGHTS; ++i)
    l_program[0].SendUniformsLightsToShader(lights[i]);
test.Draw();
glUseProgram(0);

glDisable(GL_DEPTH_TEST);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_SRC_ONE_MINUS_ALPHA);

glUseProgram(light_source.id); //Draw "point lights" 
for(int i=0; i<MAX_LIGHTS; ++i){
    if(lights[i].active){
        mvp = projection*view*lights[i].ModelMatrix(); //Estan en coordenadas de vista
        light_source.SendUniformsMatricesToShader();
        light_source.SendUniformsColorToShader(lights[i].GetColor());
        lights[i].Draw();
    }
}
glUseProgram(0);
glDisable(GL_BLEND);
glEnable(GL_DEPTH_TEST);
glutSwapBuffers();
}

片段着色器：

#version 400

uniform vec4 color;

void main(){
     gl_FragColor = color;
}