1.代码

#define PI 3.1415926

vec3 FullLineX(vec2 uv,float x){
    if(uv.x >= x && uv.x < x + 0.005){
        return vec3(1.0,0.0,0.0);
    }
    return vec3(0.0,0.0,0.0);
}

vec3 FullLineY(vec2 uv,float y){
    if(uv.y >= y && uv.y < y + 0.005){
        return vec3(1.0,0.0,0.0);
    }
    return vec3(0.0,0.0,0.0);
}

vec3 GridX(vec2 uv){
    vec3 c = vec3(0.0,0.0,0.0);
    for(float x = -0.5;x <= 0.5;x += 0.1){
        c += FullLineX(uv,x);
    }
    for(float y = -0.5;y <= 0.5;y += 0.1){
        c += FullLineY(uv,y);
    }
    return c;
}

mat2 rotate2d(float angle)
{
    mat2 m = mat2(cos(angle),-sin(angle),sin(angle),cos(angle));
    return m;
}

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
    // Normalized pixel coordinates (from 0 to 1)
    vec2 uv = fragCoord.xy / iResolution.xy;
    uv -= 0.5;
    uv = uv * rotate2d(iTime / PI * 0.5);
    vec3 c = GridX(uv);

    fragColor = vec4(c,1.0);
}

没变换的:

变换后的