Opengl 阴影映射和深度值混淆

我正在延迟OpenGL 4.3渲染器中为聚光灯进行阴影映射

我一直在尝试跟随一些关于这个主题的教程，并在之后用片段着色器建模，但我不理解的是计算阴影因子的最终比较。我从深度贴图（“

unifShadowTexture

”）中采样的值在[0,1]的范围内，因为它直接来自深度缓冲区，但是

projCoords.z

如何钳制到[0,1]？除法是否被

.w

钳制为[0,1]？ 我面临的问题是，在下图中，场景的主要部分被阴影遮挡，即使它不应该被遮挡，例如底层（忽略灯光瑕疵，因为缺少偏移-重要的一点是模型被照亮，但底层没有）：

const std:：string gDirLightFragmentShader=
“#版本430\n\
\n\
布局（std140）统一；\n\
\n\
均匀光照\n\
{\n\
mat4 mWVPMatrix；\n\
mat4 MVP矩阵；//灯光视图投影矩阵，预乘以偏移矩阵\n\
vec4 mLightColor；\n\
vec4 mLightDir；\n\
vec4-mGamma；\n\
vec2 mScreenSize；\n\
}UnifDirLightPass；\n\
\n\
布局（绑定=2）统一采样器2D unifPositionTexture；\n\
布局（绑定=3）统一采样器2D unifNormalTexture；\n\
布局（绑定=4）统一采样器2D unifDiffuseTexture；\n\
布局（绑定=5）统一采样器2D unifShadowTexture；\n\
\n\
输出vec4 fragColor；\n\
\n\
void main（）\n\
{\n\
vec2 texcoord=gl_FragCoord.xy/UnifDirLightPass.mScreenSize；\n\
\n\
vec3 worldPos=纹理（UnifiPositionTexture，texcoord）.xyz；\n\
vec3 normal=规格化（纹理（unifNormalTexture，texcoord）.xyz）；\n\
vec3漫反射=纹理（unifDiffuseTexture，texcoord）.xyz；\n\
\n\
vec4 lightClipPos=UnifDirLightPass.mVPMatrix*vec4（worldPos，1.0）；\n\
vec3 projCoords=lightClipPos.xyz/lightClipPos.w；\n\
\n\
浮点深度值=纹理（unifShadowTexture，projCoords.xy）.x；\n\
浮动可见性=1.0；\n\
如果（深度值<（projCoords.z））\n\
可见性=0.0；\n\
\n\
浮动角度法线=钳制（点（法线，UnifDirLightPass.mLightDir.xyz），0,1）；
const std::string gDirLightFragmentShader =
"#version 430                                                                                                                   \n \
                                                                                                                                \n \
layout(std140) uniform;                                                                                                         \n \
                                                                                                                                \n \
uniform UnifDirLight                                                                                                            \n \
{                                                                                                                               \n \
    mat4 mWVPMatrix;                                                                                                            \n \
    mat4 mVPMatrix;   // light view-projection matrix, pre-multiplied by the bias-matrix                                                                                                          \n \
    vec4 mLightColor;                                                                                                           \n \
    vec4 mLightDir;                                                                                                             \n \
    vec4 mGamma;                                                                                                                \n \
    vec2 mScreenSize;                                                                                                           \n \
} UnifDirLightPass;                                                                                                             \n \
                                                                                                                                \n \
layout (binding = 2) uniform sampler2D unifPositionTexture;                                                                     \n \
layout (binding = 3) uniform sampler2D unifNormalTexture;                                                                       \n \
layout (binding = 4) uniform sampler2D unifDiffuseTexture;                                                                      \n \
layout (binding = 5) uniform sampler2D unifShadowTexture;                                                                       \n \
                                                                                                                                \n \
out vec4 fragColor;                                                                                                             \n \
                                                                                                                                \n \
void main()                                                                                                                     \n \
{                                                                                                                               \n \
    vec2 texcoord = gl_FragCoord.xy / UnifDirLightPass.mScreenSize;                                                             \n \
                                                                                                                                \n \
    vec3 worldPos = texture(unifPositionTexture, texcoord).xyz;                                                                 \n \
    vec3 normal   = normalize(texture(unifNormalTexture, texcoord).xyz);                                                        \n \
    vec3 diffuse  = texture(unifDiffuseTexture, texcoord).xyz;                                                                  \n \
                                                                                                                                \n \
    vec4 lightClipPos = UnifDirLightPass.mVPMatrix * vec4(worldPos, 1.0);                                                      \n \
    vec3 projCoords   = lightClipPos.xyz / lightClipPos.w;                                                                   \n \
                                                                                                                                \n \
    float depthValue = texture(unifShadowTexture, projCoords.xy).x;                                                           \n \
    float visibilty  = 1.0;                                                                                                   \n \
    if (depthValue < (projCoords.z))                                                                                  \n \
         visibilty = 0.0;                                                                                                    \n \
                                                                                                                                \n \
    float angleNormal = clamp(dot(normal, UnifDirLightPass.mLightDir.xyz), 0, 1);                                               \n \
                                                                                                                                \n \
    fragColor = vec4(diffuse, 1.0) * visibilty * angleNormal * UnifDirLightPass.mLightColor;                                 \n \
}                                                                                                                               \n";

float depthValue = texture(unifShadowTexture, projCoords.xy).x;
float visibilty  = 1.0;

if (depthValue < (projCoords.z))
  visibilty = 0.0;            

float visibility = texture (unifShadowTexture, projCoords);