opengl - 切线空间法线贴图-着色器完整性检查

Question

我从切线空间法线贴图着色器中得到了一些非常奇特的结果:)。在这里显示的场景中，茶壶和方格墙正在使用我的普通Phong-Blinn着色器进行着色(显然，茶壶背面剔除器使它具有短暂的外观:-)。我尝试将法线贴图添加到球体中，并产生迷幻效果:

光线从右侧发出(几乎可见为黑色 Blob )。我在球体上使用的法线贴图如下所示:

我正在使用AssImp处理输入模型，因此它会自动为我计算每个顶点的切线和双法线。

像素和顶点着色器在下面。我不太确定出了什么问题，但是如果正切基矩阵某种程度上出了错，也不会令我感到惊讶。我假设我必须将事物计算到眼睛空间中，然后将眼睛和光向量转换为切线空间，这是解决该问题的正确方法。请注意，光源位置已进入 View 空间中的着色器。

// Vertex Shader
#version 420

// Uniform Buffer Structures

// Camera.
layout (std140) uniform Camera
{
    mat4 Camera_Projection; 
    mat4 Camera_View;
};

// Matrices per model.
layout (std140) uniform Model
{
    mat4 Model_ViewModelSpace;
    mat4 Model_ViewModelSpaceInverseTranspose;
};

// Spotlight.
layout (std140) uniform OmniLight
{
    float Light_Intensity;

    vec3 Light_Position;            // Already in view space.
    vec4 Light_Ambient_Colour;
    vec4 Light_Diffuse_Colour;
    vec4 Light_Specular_Colour;
};

// Streams (per vertex)
layout(location = 0) in vec3 attrib_Position;
layout(location = 1) in vec3 attrib_Normal;
layout(location = 2) in vec3 attrib_Tangent;
layout(location = 3) in vec3 attrib_BiNormal;
layout(location = 4) in vec2 attrib_Texture;

// Output streams (per vertex)
out vec3 attrib_Fragment_Normal;
out vec4 attrib_Fragment_Position;
out vec3 attrib_Fragment_Light;
out vec3 attrib_Fragment_Eye;

// Shared.
out vec2 varying_TextureCoord;

// Main
void main()
{
    // Compute normal.
    attrib_Fragment_Normal = (Model_ViewModelSpaceInverseTranspose * vec4(attrib_Normal, 0.0)).xyz;

    // Compute position.
    vec4 position = Model_ViewModelSpace * vec4(attrib_Position, 1.0);

    // Generate matrix for tangent basis.
    mat3 tangentBasis = mat3(   attrib_Tangent, 
                                attrib_BiNormal, 
                                attrib_Normal);

    // Light vector.
    attrib_Fragment_Light = tangentBasis * normalize(Light_Position - position.xyz);

    // Eye vector.
    attrib_Fragment_Eye = tangentBasis * normalize(-position.xyz);

    // Return position.
    gl_Position = Camera_Projection * position;
}

...，像素着色器如下所示:

// Pixel Shader
#version 420

// Samplers
uniform sampler2D Map_Normal;

// Global Uniforms

// Material.
layout (std140) uniform Material
{
    vec4  Material_Ambient_Colour;
    vec4  Material_Diffuse_Colour;
    vec4  Material_Specular_Colour;
    vec4  Material_Emissive_Colour;

    float Material_Shininess;
    float Material_Strength;
};

// Spotlight.
layout (std140) uniform OmniLight
{
    float Light_Intensity;

    vec3 Light_Position;    
    vec4 Light_Ambient_Colour;
    vec4 Light_Diffuse_Colour;
    vec4 Light_Specular_Colour;
};

// Input streams (per vertex)
in vec3 attrib_Fragment_Normal;
in vec3 attrib_Fragment_Position;
in vec3 attrib_Fragment_Light;
in vec3 attrib_Fragment_Eye;

// Shared.
in vec2 varying_TextureCoord;

// Result
out vec4 Out_Colour;

// Main
void main(void)
{
    // Compute normals.
    vec3 N = normalize(texture(Map_Normal, varying_TextureCoord).xyz * 2.0 - 1.0);  
    vec3 L = normalize(attrib_Fragment_Light);
    vec3 V = normalize(attrib_Fragment_Eye);
    vec3 R = normalize(-reflect(L, N));

    // Compute products.
    float NdotL = max(0.0, dot(N, L));
    float RdotV = max(0.0, dot(R, V));

    // Compute final colours.
    vec4 ambient  = Light_Ambient_Colour * Material_Ambient_Colour;
    vec4 diffuse  = Light_Diffuse_Colour * Material_Diffuse_Colour * NdotL;
    vec4 specular = Light_Specular_Colour * Material_Specular_Colour * (pow(RdotV, Material_Shininess) * Material_Strength);

    // Final colour.
    Out_Colour = ambient + diffuse + specular;      
}

编辑:3D Studio渲染场景(以显示球面上的UV正常):

Answer 1

我认为您的着色器还可以，但是您在球体上的纹理坐标完全不可用。好像它们在经度上向两极扭曲。