1

我对 opengl 和 GLSL 相当有经验。对于我的引擎，我想实现延迟照明，因为我知道这不是一项简单的任务。几个小时后，我能够让大部分工作正常进行。这是我渲染的所有缓冲区的屏幕截图：

在此处输入图像描述 左上是法线，右上是反照率，左下是位置，右下是最终渲染。（现在只渲染一盏灯。）我使用各种着色器将所有东西渲染到帧缓冲区。我以前使用过前向渲染光照着色器。为了希望提供相同的结果，我使用来自该顶点着色器的相同数据来渲染不同的缓冲区。与前向渲染器不同，光源会根据相机的位置移动和变化。这是顶点着色器的代码（片段只是渲染从顶点获得的像素）

位置着色器：

varying vec4 pos;
void main(void)
{
    gl_Position =gl_ModelViewProjectionMatrix*gl_Vertex;
    pos = gl_ModelViewMatrix*gl_Vertex;
}

普通着色器

varying vec3 normal;
void main(void)
{
     gl_Position =gl_ModelViewProjectionMatrix*gl_Vertex;
    normal = normalize(gl_NormalMatrix*gl_Normal);
}

对于反照率，我只使用 opengl 的常规着色器并绑定纹理。

这是最终的光照着色器，它在屏幕上呈现为四边形：

uniform sampler2D positionMap;
uniform sampler2D normalMap;
uniform sampler2D albedoMap;
varying vec2 texcoord;
uniform mat4 matrix;
void main()
{
    vec3 position = vec3(texture2D(positionMap,texcoord));
    vec3 normal = vec3(texture2D(normalMap,texcoord));

    vec3 L = normalize(gl_LightSource[0].position.xyz - position);
    float l = length(L)/5.0;
    float att = 1.0/(l*l+l);

    //render sun light
    vec4 diffuselight = max(dot(normal,L), 0.0)*vec4(att,att,att,att);
    diffuselight = clamp(diffuselight, 0.0, 1.0)*2.0;
    vec4 amb = vec4(.2,.2,.2,0);

    vec4 texture = texture2D(albedoMap,texcoord);

    gl_FragColor =  ((diffuselight)+amb)*texture;

}

这里面有很多其他地方引用的功能，不过我想大家可以从图片和代码中得到大致的依据。这是主要的渲染功能：

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

//render skybox
glLoadIdentity();
renderSkybox();
//skybox.renderObject();
glLoadIdentity();
renderViewModel();


renderCamera();
glMatrixMode(GL_MODELVIEW);
GLfloat position[] = {-Lighting.x,-Lighting.y,-Lighting.z,1};
glLightfv(GL_LIGHT0, GL_POSITION, position);
glDisable(GL_LIGHTING);

glm::mat4 modelView,projection,final;
glGetFloatv(GL_MODELVIEW_MATRIX, &modelView[0][0]);
glGetFloatv(GL_PROJECTION_MATRIX, &projection[0][0]);
final=modelView*projection;

Lighting.setupDepthImage();
glLoadIdentity();

for (int i = 0; i < objects.size(); i++)
{
   objects[i].renderObjectForDepth();
}
    Lighting.finishDepthImage();

//render the 3 buffers

//normal buffer
glBindFramebuffer(GL_FRAMEBUFFER, Lighting.Normal.frameBuffer);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
for (int i = 0; i < objects.size(); i++)
{
  objects[i].renderObjectWithProgram(Lighting.normalShader);
}
//albedo
glBindFramebuffer(GL_FRAMEBUFFER, Lighting.Albedo.frameBuffer);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
for (int i = 0; i < objects.size(); i++)
{
    objects[i].renderObjectWithProgram(0);
}
//position
glBindFramebuffer(GL_FRAMEBUFFER, Lighting.Position.frameBuffer);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
for (int i = 0; i < objects.size(); i++)
{
    objects[i].renderObjectWithProgram(Lighting.positionShader);
}
//go back to rendering directly to the screen
 glBindFramebuffer(GL_FRAMEBUFFER, 0);


renderCamera();
glTranslatef(-test.position.x, test.position.y, -test.position.z);
test.updateParticle(1);

//render the buffers for debugging
renderViewModel();
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 1280, 800, 0, -1, 1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

//render the full screen quad for the sun
glUseProgram(Lighting.sunShader);

glUniform1i(glGetUniformLocation(Lighting.sunShader,"normalMap"),0);
glUniform1i(glGetUniformLocation(Lighting.sunShader,"albedoMap"),1);
glUniform1i(glGetUniformLocation(Lighting.sunShader,"positionMap"),2);
glUniformMatrix4fv(glGetUniformLocation(Lighting.sunShader, "matrix"), 1, GL_FALSE, &final[0][0]);

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, Lighting.Normal.texture);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, Lighting.Albedo.texture);
glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, Lighting.Position.texture);




glBindFramebuffer(GL_FRAMEBUFFER, Lighting.debugFinal.frameBuffer);
 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBegin(GL_QUADS);
glTexCoord2f(0, 1);
glVertex2f(0, 0);
glTexCoord2f(1, 1);
glVertex2f(1280, 0);
glTexCoord2f(1, 0);
glVertex2f(1280, 800);
glTexCoord2f(0, 0);
glVertex2f(0, 800);
glEnd();

glBindFramebuffer(GL_FRAMEBUFFER, 0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, 0);

glUseProgram(0);
//normals
glBindTexture(GL_TEXTURE_2D,Lighting.Normal.texture);
glBegin(GL_QUADS);
glTexCoord2f(0, 1);
glVertex2f(0, 0);
glTexCoord2f(1, 1);
glVertex2f(640, 0);
glTexCoord2f(1, 0);
glVertex2f(640, 400);
glTexCoord2f(0, 0);
glVertex2f(0, 400);
glEnd();
//albedo
glBindTexture(GL_TEXTURE_2D,Lighting.Albedo.texture);
glBegin(GL_QUADS);
glTexCoord2f(0, 1);
glVertex2f(640, 0);
glTexCoord2f(1, 1);
glVertex2f(1280, 0);
glTexCoord2f(1, 0);
glVertex2f(1280, 400);
glTexCoord2f(0, 0);
glVertex2f(640, 400);
glEnd();
//position
glBindTexture(GL_TEXTURE_2D,Lighting.Position.texture);
glBegin(GL_QUADS);
glTexCoord2f(0, 1);
glVertex2f(0, 400);
glTexCoord2f(1, 1);
glVertex2f(640, 400);
glTexCoord2f(1, 0);
glVertex2f(640, 800);
glTexCoord2f(0, 0);
glVertex2f(0, 800);
glEnd();
//final image
glBindTexture(GL_TEXTURE_2D,Lighting.debugFinal.texture);
glBegin(GL_QUADS);
glTexCoord2f(0, 1);
glVertex2f(640, 400);
glTexCoord2f(1, 1);
glVertex2f(1280, 400);
glTexCoord2f(1, 0);
glVertex2f(1280, 800);
glTexCoord2f(0, 0);
glVertex2f(640, 800);
glEnd();
View3D();



SDL_GL_SwapWindow(window);
glLoadIdentity();

这里有一些无关的东西，忽略它们。如您所见，我使用 GLSL 的默认方法获得了灯光的位置。我认为因为我处于正交视图中，所以有些东西与灯光的位置有关。这可能是问题所在，还是有其他问题，可能是在计算法线等？

4

1 回答 1

1

人们可能不会觉得这很有用，但我已经解决了我的问题。我使用常规的 opengl 灯在着色器中进行照明。当我设置位置时，我将 w 值设为 1，这将使它成为定向光，而不是点光，因此赋予光移动行为。

另一方面，我改变了从深度缓冲区重建的位置以及其他一些改进 G 缓冲区的东西。

于 2013-10-12T16:48:49.077 回答