Question

我正在尝试实现基于后处理运动矢量的运动模糊。它有点“有效”......

我遇到了两个主要问题：

如果对象和相机都没有移动，则图形会产生空白屏幕。
屏幕边框上有物体扭曲。

这是2遍方法：传递＃1 - 将对象渲染到FBO texture.pass＃2 - 渲染到全屏四边形并将MB应用于上一个传递输出。

第二遍的顶点着色器：

void main(void){
    // transform previous and current position to eye space
    vec4 P =     MODEL_VIEW_MATRIX * position;
    vec4 Pprev = prevModelView * position;
    vec3 motionVector = P.xyz - Pprev.xyz;

    // calculate window space motion vector
    P =           PROJ  * MODEL_VIEW_MATRIX * position;
    Pprev =       PROJ * prevModelView * position;
    Pprev = mix(P, Pprev, blurScale);

    // choose previous or current position based on dot product between motion vector 
    // and normal
    vec3 N = mat3(MODEL_VIEW_MATRIX) *normal;
    bool flag = dot(motionVector, N) > 0;
    vec4 Pstretch = flag ? P : Pprev;
    gl_Position =  position;

    // do divide by W -> NDC coordinates
    P.xyz = P.xyz / P.w;
    Pprev.xyz = Pprev.xyz / Pprev.w;

    // calculate window space velocity
    vec3 dP = (P.xyz - Pprev.xyz) * halfWindowSize.xyz;
    float len = length (dP)/(halfWindowSize[0]*2);
    len = clamp(len, 0., 1.);
    dP =  normalize(dP);
    dP.z = len; 
    out_velocity = dP;
}

第二遍的片段着色器：

void main(void){
    float w = 1.0 / samples;        
    vec4 a=vec4(0.);
    vec2 velocity = out_velocity.xy * blurScale * .05 * out_velocity.z;

    ivec2 tsize = textureSize(COLOR_MAP_0, 0);
    vec2 screntc = gl_FragCoord.xy * (1.0 / vec2(tsize));

    // sample into scene texture along motion vector 
    for(float i=0; i<samples; i+=1) 
    {
        float t = i / (samples-1);
        a = a + texture(COLOR_MAP_0, vec2(screntc)  + velocity * t ) * w;               
    }

    colorOut = a;
 }

这些着色器有什么问题？

OpenGL屏幕空间运动模糊

0 个答案: