C++与阴影矩阵比较,不产生阴影

我正在尝试实现阴影映射。我能够在帧缓冲区纹理上渲染深度贴图。并将其发送到着色器以及灯光正交矩阵,以测试阴影中是否有碎片。但结果并不正确。不是创建阴影,而是将所有碎片单独绘制,如果它们“位于”光线矩阵的内部。

正如您在左下角看到的,生成的深度纹理是正确的。

我试过很多教程,但都没有提到像这样的问题。这可能是因为光线方向和正交投影是错误的,但我似乎找不到一个产生阴影的工作光线方向。

这就是生成帧缓冲区和纹理的方式(在类标题中实例化了帧缓冲区和帧缓冲区纹理):

glGenFramebuffers(1, &frameBuffer);
glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer);

//texture buffer for frame buffer
glGenTextures(1, &framebufferTexture);
glBindTexture(GL_TEXTURE_2D, framebufferTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT16, 896, 504, 0, GL_DEPTH_COMPONENT, GL_FLOAT, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_FUNC, GL_LESS);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_COMPARE_REF_TO_TEXTURE);


//Set framebufferTexture as our color attachment #0
glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
    GL_TEXTURE_2D, framebufferTexture, 0);

glDrawBuffer(GL_NONE);

这就是我创建深度纹理的方式

glCullFace(GL_BACK);
glBindFramebuffer(GL_DRAW_FRAMEBUFFER, frameBuffer);
//Setup depth texture framebuffer rendering
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonOffset(2.0f, 2.0f);
glViewport(0, 0, 896, 504);
glClear(GL_DEPTH_BUFFER_BIT);

glUniform1i(glGetUniformLocation(shaderProgram, "fragmentTypeTarget"), -1);


glm::vec3 lightInvDir = glm::vec3(5, 17, 1);
//Calculate the matrix for drawing the framebuffer
//Make it an orthographic that takes the whole screen
glm::mat4 depthProjectionMatrix = glm::ortho<float>(-17, 17, -17, 17, 0, 37);
glm::mat4 depthViewMatrix = glm::lookAt(
    lightInvDir,
    glm::vec3(0, 0, 0),
    glm::vec3(0, 1, 0));
glm::mat4 lightSpaceMatrix = depthProjectionMatrix * depthViewMatrix;

//Render the objects
for (int i = 0; i < objectPool.size(); i++) {
    objectPool[i]->draw(lightSpaceMatrix);
}

以下是我发送阴影贴图矩阵以绘制阴影的方式:

glm::mat4 Model = glm::translate(glm::mat4(1.0), glm::vec3(x, y, z));
glm::vec3 lightInvDir = glm::vec3(5, 17, 1);
    //Calculate the matrix for drawing the framebuffer
    //Make it an orthographic that takes the whole screen
    glm::mat4 depthProjectionMatrix = glm::ortho<float>(-17, 17, -17, 17, 0, 37);
    glm::mat4 depthViewMatrix = glm::lookAt(
        lightInvDir,
        glm::vec3(0, 0, 0),
        glm::vec3(0, 1, 0));
    glm::mat4 lightSpaceMatrix = depthProjectionMatrix * depthViewMatrix * Model;
glUniformMatrix4fv(glGetUniformLocation(shader, "shadowMatrix"), 1, GL_FALSE, &lightSpaceMatrix[0][0]);

我的片段着色器:

#version 330 core
layout(location = 0) out vec4 outColor;
in vec2 UV;
in vec4 ShadowCoord;
uniform sampler2D textureSampler;
uniform sampler2D shadowMap;
uniform int fragmentTypeTarget;


// 'colorImage' is a sampler2D with the depth image
// read from the current depth buffer bound to it.
float LinearizeDepth(in vec2 uv, sampler2D t)
{
    float zNear = 1.0;    
    float zFar  = 5.0; 
    float depth = texture2D(t, uv).x;
    return (2.0 * zNear) / (zFar + zNear - depth * (zFar - zNear));
}

void main(){
if(fragmentTypeTarget == -1){//draw frame buffer

}else if(fragmentTypeTarget == 0){//Draw everything normal
    vec4 tex = texture2D(textureSampler, UV);
    outColor = vec4(tex.rgb, tex.a);
}else if(fragmentTypeTarget == 1){//Draw depth texture
    //vec2 res = gl_FragCoord.xy / vec2(1024, 1024);
    outColor = texture(textureSampler, UV);
    float c = LinearizeDepth(UV, textureSampler);
    outColor = vec4(c, c, c, 1.0);
}else if(fragmentTypeTarget == 2){//Draw everything but apply the shadow
    float visibility = 1.0;
    float bias = 0.0039;

    if(texture(shadowMap, ShadowCoord.xy).z < ShadowCoord.z){
        visibility = 0.3;
    }
    vec4 tex = texture2D(textureSampler, UV);
    outColor = visibility * vec4(tex.rgb, tex.a);
}
}

#version 330 core
in vec2 UVsIn;
out vec2 UV;
in vec3 position;
in vec3 vertexColor;
out vec3 fragmentColor;
uniform mat4 mvp;
uniform mat4 shadowMatrix;
out vec4 ShadowCoord;

void main(){
gl_Position = mvp * vec4(position, 1.0);
fragmentColor = vertexColor;
UV = UVsIn;

ShadowCoord = shadowMatrix * vec4(position, 1.0);
}

结果应该更像这样:

编辑:

生成帧缓冲区纹理时,我使用了错误的比较函数。应该是“GL\u COMPARE\u R\u TO\u TEXTURE”,而不是“GL\u COMPARE\u REF\u TO\u TEXTURE”。

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_COMPARE_R_TO_TEXTURE);

这正是我想要的。

我还发现纹理坐标是(s,t,r)而不是(x,y,z)。

因为我想比较矩阵和纹理的深度,所以我需要使用r而不是z。 因此片段着色器的编写方式应如下所示:

float visibility = 1.0;

vec2 mapUV = ShadowCoord.xy * 0.5 + 0.5;
float depthFrag = ShadowCoord.z * 0.5 + 0.5;

float depthMap = texture(shadowMap, mapUV).r;//r instead of z since its (s, t, r)

if(depthMap < depthFrag){
    visibility = 0.3;
}

vec4 tex = texture2D(textureSampler, UV);
outColor = visibility * vec4(tex.rgb, tex.a);

Rabbi76回复中还需要添加“*0.5+0.5”。