#version 450

layout (binding = 1) uniform sampler2D samplerColor;
layout (binding = 2) uniform sampler2D samplerColor_ex;

layout (location = 0) in vec2 inUV;
layout (location = 1) in vec3 inNormal;


layout (location = 0) out vec4 outFragColor;

void main() 
{
	vec4 color = texture(samplerColor, inUV);
	vec4 color_ex = texture(samplerColor_ex, inUV);

	vec3 N = normalize(inNormal);

    // 计算与 (0,0,1) 的点乘
    float ndot = dot(N, vec3(0.0, 0.0, -1.0));

	// 保证结果 >= 0
    ndot = max(ndot, 0.0);
    
    // 重新映射ndot值，让中间2/3部分进行融合
    // 当ndot在[0.166, 0.833]范围内时进行混合，两端保持不变
    float blendFactor;
    if (ndot < 0.0) {
       blendFactor = 0.0; // 完全使用color_ex
    } else if (ndot > 0.1) {
       blendFactor = 1.0; // 完全使用color
    } else {
       // 在中间2/3部分进行平滑过渡
       blendFactor = (ndot - 0.0) / (1 - 0);
    }

	// 使用smoothstep创建中间2/3的融合区域
    // 参数说明：smoothstep(edge0, edge1, x)
    // 当x < edge0时返回0，当x > edge1时返回1，在中间时平滑过渡
    //float blendFactor = smoothstep(0.166, 0.833, ndot);
    
    
    // vec4 blendedColor = mix(color_ex, color, ndot);

	// outFragColor = blendedColor;

    if (ndot < 0.3){
        outFragColor = color_ex;
    }
    else
    {
        outFragColor = color;
    }

//	outFragColor = vec4(1, 0, 0, 1);
}