使用 OpenGL 使用延迟渲染绑定 FBO 后卡在渲染灯上

Posted 2023-02-22

【中文标题】使用 OpenGL 使用延迟渲染绑定 FBO 后卡在渲染灯上

【英文标题】：Stuck on rendering lights after binding FBO using deffered rendering using OpenGL

【发布时间】：2016-01-30 04:52:28

【问题描述】：

首先我很抱歉在尝试了一整天的工作后写了这么长的帖子。

我对此有很多疑问，尤其是因为我在 C++ 中使用继承来构建灯光。

我使用定向光作为光的核心模型，因为我可以给出光的方向，它会计算光，然后在它之上我构建点光，我只计算从光到片段位置的矢量，最后对于聚光灯，我使用带有截止角的点光来创建聚光灯（只需忽略圆锥外的任何东西）。我已经测试了灯光，它们在前向渲染中工作得很好，但现在我想将我的灯光模型更改为 PBR（基本上只是改变我在定向光中计算灯光的方式）并转向不同的渲染。

今天我开始研究延迟渲染，我可以获得位置、纹理、法线和深度缓冲区，但是在尝试渲染灯光时遇到了问题。

这是第一个问题，第二个问题，因为每种类型的光都有自己的着色器，我使用多态性构建它们。我的第二个问题是我可以循环遍历 C++ 中的每个灯光并将每个灯光称为渲染器，或者还有另一种方法可以在着色器中解决这个问题。 灯的原型是 编辑：我修复了一个小问题，即 iw 用 VP 投影转换渲染 quat，但我仍然无法绘制任何东西，我不知道 FB 现在是否工作正常。 Nvidia opengl 调试器正在崩溃。

 Light(glm::vec3& color, float intensity, float ambient, ShaderProgram& lightShader);
 DirectionalLight(glm::vec3& color = glm::vec3(1.0f, 1.0f, 1.0f), glm::vec3& position = glm::vec3(0.0f, 0.0f, 0.0f), float intensity = 1.0f, float ambient = 0.0f, ShaderProgram& lightShader = ShaderProgram("Directional Light"));
    PointLight(glm::vec3& color = glm::vec3(1.0f, 1.0f, 1.0f), glm::vec3& position = glm::vec3(0.0f, 0.0f, 0.0f), float intensity = 1.0f, float ambient = 0.0f, LightAttenuation& lightAttenuation = LightAttenuation(), ShaderProgram& lightShader = ShaderProgram("Point Light"));
 SpotLight(glm::vec3& color = glm::vec3(1.0f, 1.0f, 1.0f), glm::vec3& position = glm::vec3(0.0f, 0.0f, 0.0f),

我的渲染路径如下所示。

            glEnable(GL_DEPTH_TEST);
            glDepthFunc(GL_LESS);

        defferedShader_.startProgram();
        defferedShader_.setUniformMat4("VP", camera.getVP());


        glBindFramebuffer(GL_FRAMEBUFFER, deferredFbo);

        //the scene is small and does not need culling.
        for (auto* mesh : world.getMeshes()) 

            //mesh->draw(light->getLightShader());
            //mesh->draw(activeLight_->getLightShader());
            mesh->draw(defferedShader_);

            drawCallCounter += mesh->getMeshObjectSize();
        

glBindFramebuffer(GL_FRAMEBUFFER, 0);
        defferedShader_.stopProgram();
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, positionFbo);
        glActiveTexture(GL_TEXTURE1);
        glBindTexture(GL_TEXTURE_2D, normalFbo);
        glActiveTexture(GL_TEXTURE2);
        glBindTexture(GL_TEXTURE_2D, albedoFbo);

               //This is where i got stuck, I would like to make directional light work then test other lights then test the whole program with more than one light
        //for (auto* light : world.getLights()) 
        //  //glEnable(GL_CULL_FACE);
        //  //glCullFace(GL_FRONT);
            glDisable(GL_DEPTH_TEST);
            activeLight_->getLightShader().startProgram();

            activeLight_->getLightShader().setUniformMat4("VP", camera.getVP());
            activeLight_->getLightShader().setUniformVec3("eyePosition", camera.getCameraPosition());

            //activeLight_->getLightShader();
            RenderQuad();

            activeLight_->getLightShader().stopProgram();

  //

我开始构建的着色器代码是（PS 我现在删除了阴影） 顶点着色器

    #version 410 core

#include "../Global/GlobalShader.inc"
#include "../Global/GlobalMesh.inc"

out vec3 Position;
out vec2 TexCoord;
//out vec4 ShadowCoord;

//uniform mat4 ShadowMatrix;

void main() 

    Position = position;
    TexCoord = texCoord;

    //ShadowCoord = ShadowMatrix * vec4(position, 1.0);
    gl_Position = VP * vec4(position, 1.0);

片段着色器 困扰我的一件事是，即使我使用它们，我也无法为 gPosition、gPosition 和 gAlbedoSpec 设置统一值，并且无论我在着色器中进行什么更改，输出都是相同的。

        #version 410 core

    #include "../Global/GlobalShader.inc"
    #include "../Global/GlobalMesh.inc"
    #include "../Global/GlobalLight.inc"
    //#include "../Global/ShadowSampling.inc"

    in vec3 Position;
    in vec2 TexCoord;
    //in vec4 ShadowCoord;

    uniform sampler2D gPosition;
    uniform sampler2D gNormal;
    uniform sampler2D gAlbedoSpec;

    float specularStrength = 32.0f; // to be impelemented

    out vec4 gl_FragColor;
    void main() 

        //vec4 lightning = vec4(0.0f);
        ////vec4 shadowMapping = vec4(0.0f);
        //
        vec3 FragPos = texture(gPosition, TexCoord).rgb;
        vec3 Normal = texture(gNormal, TexCoord).rgb;
        vec3 Diffuse = texture(gAlbedoSpec, TexCoord).rgb;
        float Specular = texture(gAlbedoSpec, TexCoord).a;

        //vec3 Diffuse = texture(gAlbedoSpec, TexCoord).rgb;
        //lightning = calculateDirectionalLight(directionalLight.light, directionalLight.position, Normal, Position, specularStrength, eyePosition, material, TexCoord);
        //gl_fragColor = vec3(Position, 1.0);
        //shadowMapping = calculateShadow(shadowMap, ShadowCoord, directionalLight.light.ambient);
        //gl_FragColor = vec4(Diffuse, 1.0);
        gl_FragColor = vec4(1.0); //vec4(Diffuse, 1.0);// lightning;//g * shadowMapping;

        //gl_FragColor = lightning;// * shadowMapping;
    

in case you want to see global light 

    struct Light

    vec3 color;
    float intensity;
    float ambient;
;

struct DirectionalLight

    Light light;
    vec3 position;
;

struct Attenuation

    float constant;
    float linear;
    float quadratic;
;

struct PointLight

    Light light;
    Attenuation atten;
    vec3 position;
    float range;
;

struct SpotLight

    PointLight pointLight;
    //vec3 lookAt;
    vec3 direction;
    float cutOff;
;

vec3 GAMMA = vec3(1.0/2.2);

vec4 calculateDirectionalLight(Light light, vec3 direction, vec3 normal, vec3 worldPosition, float specularIntensity, vec3 eyePosition, Material material, vec2 texCoord)

        vec3 diffuseFactor = ( light.color * material.diffuse * vec3(texture(material.texture.diffuse, texCoord.st)) )
                                                 * (light.intensity * clamp(dot(normal, direction), 0.0, 1.0) ) ;

        vec3 viewDir = normalize(eyePosition - worldPosition);
        vec3 reflectDir = normalize(reflect(-direction, normal));

        float specularFactor = pow(clamp(dot(viewDir, reflectDir), 0.0, 1.0), specularIntensity);
        vec3 specularColor = ( light.color * material.specular * vec3(texture(material.texture.specular, texCoord.st)) ) * (specularFactor * material.shininess);

        return vec4(pow((diffuseFactor + specularColor + light.ambient + material.ambient), GAMMA), 1.0);


vec4 calculatePointLight(PointLight pointLight, vec3 normal, vec3 worldPosition, float specularIntensity, vec3 eyePosition, Material material, vec2 texCoord)

        // DO NOT NORMALIZE lightDirection, WE NEED IT TO CALCULATE THE DISTANCE TO COMPARE RANGE OF LIGHT
        vec3 lightDirection = pointLight.position - worldPosition;
        float distanceToPoint = length(lightDirection);

        // I dont like conditionals in shader, but since this is fragment based lighting i believe
        // this will speed-up things insetead of calculating the light
        if(distanceToPoint > pointLight.range)
                return vec4(0.0,0.0,0.0,0.0);

        vec4 light = calculateDirectionalLight(pointLight.light, lightDirection, normal, worldPosition,  specularIntensity, eyePosition, material, texCoord);

        // light attenuateion explained https://developer.valvesoftware.com/wiki/Constant-Linear-Quadratic_Falloff
        // http://www.ogre3d.org/tikiwiki/tiki-index.php?page=Light+Attenuation+Shortcut
        float attenuation = max(pointLight.atten.constant
                                + pointLight.atten.linear * distanceToPoint
                                + pointLight.atten.quadratic * distanceToPoint * distanceToPoint,
                                1.0);

    return light / attenuation;


vec4 calculateSpotLight(SpotLight spotLight, vec3 normal, vec3 worldPosition, float specularIntensity, vec3 eyePosition, Material material, vec2 texCoord) 

    vec3 lightDirection = normalize(spotLight.pointLight.position - worldPosition);
    float spotFactor = dot(lightDirection, spotLight.direction);

    vec4 light = vec4(0.0f);
    if(spotFactor > spotLight.cutOff)
    
        light = calculatePointLight(spotLight.pointLight, normal, worldPosition, specularIntensity, eyePosition, material, texCoord) * (1.0 - (1.0 - spotFactor)/(1.0 - spotLight.cutOff));
    

    return light;

全局网格

   struct Texture 
    sampler2D diffuse;
    sampler2D specular;
    sampler2D normal;
    sampler2D ambient;
    sampler2D height;
    //vec2 texCoord;            
;

struct Material 
    vec3 ambient;           // Ka
    vec3 diffuse;           // Kd
    vec3 specular;          // Ks
    vec3 transmittance;     // Tr
    vec3 emission;          // Ke
    float shininess;        // Ns
    float ior;              // Ni
    float dissolve;         // Dissolve
    int illum;              // Illum
    Texture texture;
;

uniform Material material;

layout (location = 0) in vec3 position;
layout (location = 1) in vec2 texCoord;
layout (location = 2) in vec3 normal;

全局着色器

    uniform mat4 VP;
uniform mat4 P;

绑定缓冲区并运行定向着色器后，我现在得到的是

作为查看场景的示例，这是位置缓冲区

【问题讨论】：

ID：opengl.org/wiki/Shader_Subroutine

【参考方案1】：

修复它。我把干净的缓冲区和颜色放在了错误的地方。它应该在我绑定缓冲区之后而不是在每一帧的开头。

glEnable(GL_DEPTH_TEST);


glBindFramebuffer(GL_FRAMEBUFFER, deferredFbo);

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    defferedShader_.startProgram();
    defferedShader_.setUniformMat4("VP", camera.getVP());
.
.
. rest of the code