如何在颤动着色器中实现从topLeft到botttomRgiht的渐变效果？

uniform float progress; // 渐变进度

void mainImage(out vec4 fragColor, in vec2 fragCoord)
{
    vec2 uv = fragCoord / iResolution.xy;
    vec2 topLeft = vec2(0.0, 0.0);
    vec2 bottomRight = vec2(1.0, 1.0);
    
    // 计算当前像素的位置
    vec2 pixelPos = mix(topLeft, bottomRight, uv);
    
    // 计算当前像素的相对位置
    float relativePos = distance(pixelPos, topLeft) / distance(topLeft, bottomRight);
    
    // 插值计算颜色
    vec3 color = mix(vec3(1.0, 0.0, 0.0), vec3(0.0, 0.0, 1.0), relativePos);
    
    fragColor = vec4(color, 1.0);
}