c++ - OpenGL ES3 阴影贴图问题

Question

我在使用 OpenGL ES3 的 Android C++ 项目上工作，所以我尝试用定向光实现阴影贴图，我很了解这个理论，但我从未成功渲染它。 首先，我创建了包含深度图的帧缓冲区:

glGenFramebuffers(1, &depthMapFBO);
glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
glGenTextures(1, &depthMap);
glBindTexture(GL_TEXTURE_2D, depthMap);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, SHADOW_WIDTH, SHADOW_HEIGHT, 0, GL_DEPTH_COMPONENT, GL_FLOAT, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depthMap, 0);
glDrawBuffers(1, GL_NONE);
glReadBuffer(GL_NONE);
glBindTexture(GL_TEXTURE_2D, 0);
glBindFramebuffer(GL_FRAMEBUFFER, 0);

然后我创建一个编译深度着色器的着色器程序，如下所示:

#version 300 es
precision mediump float;

layout (location = 0) in vec3 position;
layout (location = 4) in ivec4 BoneIDs;
layout (location = 5) in vec4 Weights;

const int MAX_BONES = 100;

uniform mat4 lightSpaceMatrix;
uniform mat4 model;
uniform bool skinned;
uniform mat4 gBones[MAX_BONES];

void main(){
vec4 nPos;
if(skinned){
    mat4 BoneTransform = gBones[BoneIDs[0]] * Weights[0];
    BoneTransform     += gBones[BoneIDs[1]] * Weights[1];
    BoneTransform     += gBones[BoneIDs[2]] * Weights[2];
    BoneTransform     += gBones[BoneIDs[3]] * Weights[3];
    nPos=BoneTransform * vec4(position, 1.0);
}
else 
    nPos = vec4(position, 1.0);

vec4 p=model * nPos;
gl_Position = lightSpaceMatrix * p;
}

并使用此着色器程序和以下光空间矩阵绘制场景:

glCullFace(GL_FRONT);
        double delta = GetCurrentTime() - firstFrame;
        glm::mat4 camInv = glm::inverse(camera->getViewMatrix());
        glm::mat4 lightSpaceProjection = glm::ortho(-40.0f, 40.0f, -40.0f, 40.0f, -1.0f, 100.0f);
        glm::mat4 lightSpaceView = glm::lookAt(sun->direction, glm::vec3(0, 0, 0), glm::vec3(0, 1, 0));
        lightSpaceMatrix = lightSpaceProjection * (lightSpaceView*camInv) ;
        glViewport(0, 0, SHADOW_WIDTH, SHADOW_HEIGHT);
        glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);

        glClear(GL_DEPTH_BUFFER_BIT);
        directDepthShader.use();
        glUniformMatrix4fv(glGetUniformLocation(directDepthShader.getProgramID(), "lightSpaceMatrix"), 1, GL_FALSE, glm::value_ptr(lightSpaceMatrix));
        for (mesh_it it = castShadowMeshes.begin(); it != castShadowMeshes.end(); it++) {
            it->get()->renderDepth(directDepthShader, delta);
        }
        glCullFace(GL_BACK);
glBindFramebuffer(GL_FRAMEBUFFER, 0);

最后，我使用常规着色器程序渲染场景，并使用以下代码将深度图绑定(bind)到 shadowMap 制服:

glViewport(0, 0, width, height);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
phongShader.use();
if (sun != nullptr)
    if (sun->castShadow)
        glUniformMatrix4fv(glGetUniformLocation(phongShader.getProgramID(), "lightSpaceMatrix"), 1, GL_FALSE, glm::value_ptr(lightSpaceMatrix));
this->setLightsUniforms(phongShader);
this->setViewUniforms(phongShader);
for (mesh_it it = phongMeshes.begin(); it != phongMeshes.end(); it++) {
    if (it->get()->hasNormalMap) {
        glUniform1i(glGetUniformLocation(phongShader.getProgramID(), "has_normal_map"), 1);
        if (directlights.size() > 0) {
            for (dlight_it it = this->directlights.begin(); it != this->directlights.end(); ++it) {
                GLuint directLightPosLoc = glGetUniformLocation(phongShader.getProgramID(), (const GLchar*) ("directLightPos[" + ToString((*it)->index) + "]").c_str());
                glUniform3f(directLightPosLoc, (*it)->direction.x, (*it)->direction.y, (*it)->direction.z);
            }
        }
        if (pointlights.size() > 0) {
            for (plight_it it = this->pointlights.begin(); it != this->pointlights.end(); ++it) {
                GLuint pointLightPosLoc = glGetUniformLocation(phongShader.getProgramID(), (const GLchar*) ("pointLightPos[" + ToString((*it)->index) + "]").c_str());
                glUniform3f(pointLightPosLoc, (*it)->position.x, (*it)->position.y, (*it)->position.z);
            }
        }
        if (spotlights.size() > 0) {
            for (slight_it it = this->spotlights.begin(); it != this->spotlights.end(); ++it) {
                GLuint spotLightPosLoc = glGetUniformLocation(phongShader.getProgramID(), (const GLchar*) ("spotLightPos[" + ToString((*it)->index) + "]").c_str());
                glUniform3f(spotLightPosLoc, (*it)->position.x, (*it)->position.y, (*it)->position.z);
            }
        }
    }
    double first = GetCurrentTime() - firstFrame;
    it->get()->textures = 0;
    if (sun != nullptr)
        if (sun->castShadow) {
            glUniform1i(glGetUniformLocation(phongShader.getProgramID(), "shadowMap"), it->get()->textures);
            glActiveTexture(GL_TEXTURE0 + it->get()->textures);
            glBindTexture(GL_TEXTURE_2D, depthMap);
            it->get()->textures++;
        }
    it->get()->Render(phongShader, first, deltaTime);
    glBindTexture(GL_TEXTURE_2D, 0);
}

最终着色器顶点和片段如下:

顶点:

#version 300 es
precision mediump float;

#define NR_DIRECT_LIGHTS 0
#define NR_POINT_LIGHTS 0
#define NR_SPOT_LIGHTS 0

layout (location = 0) in vec3 position;
layout (location = 1) in vec3 normal;
layout (location = 2) in vec2 texCoord;
layout (location = 3) in vec3 tangent;
layout (location = 4) in ivec4 BoneIDs;
layout (location = 5) in vec4 Weights;

const int MAX_BONES = 100;

out vec2 TexCoords;
out vec3 Normal;
out vec3 tDirectLightPos[NR_DIRECT_LIGHTS];
out vec3 tPointLightPos[NR_POINT_LIGHTS];
out vec3 tSpotLightPos[NR_SPOT_LIGHTS];
out vec3 tViewPos;
out vec3 tFragPos;
out vec4 FragPosLightSpace;

// conditions //
uniform bool has_normal_map;    
uniform bool skinned;
//

uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
uniform vec3 viewPos;
uniform mat4 lightSpaceMatrix;  
uniform mat4 gBones[MAX_BONES];

uniform vec3 directLightPos[NR_DIRECT_LIGHTS];
uniform vec3 pointLightPos[NR_POINT_LIGHTS];
uniform vec3 spotLightPos[NR_SPOT_LIGHTS];

void main(){    
    TexCoords = texCoord;
    vec4 nPos;
    vec3 N=transpose(inverse(mat3(model))) * normal;
    if(skinned){
        mat4 BoneTransform = gBones[BoneIDs[0]] * Weights[0];
        BoneTransform     += gBones[BoneIDs[1]] * Weights[1];
        BoneTransform     += gBones[BoneIDs[2]] * Weights[2];
        BoneTransform     += gBones[BoneIDs[3]] * Weights[3];
        nPos=BoneTransform * vec4(position, 1.0);   
        Normal=(BoneTransform*vec4(N,0.0)).xyz; 
    }
    else{
        nPos = vec4(position, 1.0);
        Normal=N;   
    }
    gl_Position = projection*view * model * nPos;

    vec3 FragPos = vec3(model * nPos);  
    if(has_normal_map){
        mat3 normalMatrix = transpose(inverse(mat3(model)));        
        vec3 T = normalize(normalMatrix * tangent);
        vec3 N = normalize(N);
        T = normalize(T - dot(T, N) * N);
        vec3 B = cross(N,T);    
        if (dot(cross(N, T), B) < 0.0)
           T = T * -1.0;    
        mat3 TBN = transpose(mat3(T, B, N));

        tViewPos=TBN*viewPos;
        tFragPos=TBN*FragPos;
        for(int i = 0; i < NR_DIRECT_LIGHTS-2; i++)
            tDirectLightPos[i]=TBN*directLightPos[i];
        for(int i = 0; i < NR_POINT_LIGHTS-2; i++)
            tPointLightPos[i]=TBN*pointLightPos[i];
        for(int i = 0; i < NR_SPOT_LIGHTS-2; i++)
            tSpotLightPos[i]=TBN*spotLightPos[i];
    }
    else{
        tViewPos=viewPos;
        tFragPos=FragPos;
    }
    FragPosLightSpace = lightSpaceMatrix * vec4(FragPos,1.0);       
}

片段:

#version 300 es
precision mediump float;

#define NR_DIRECT_LIGHTS 0
#define NR_POINT_LIGHTS 0
#define NR_SPOT_LIGHTS 0

out vec4 glFragColor;

vec2 poissonDisk[4] = vec2[](
vec2( -0.94201624, -0.39906216 ),
vec2( 0.94558609, -0.76890725 ),
vec2( -0.094184101, -0.92938870 ),
vec2( 0.34495938, 0.29387760 )
);
struct SpotLight{
    vec3 position;
    vec3 direction;
    vec3 color;

    float constant;
    float linear;
    float quadratic;
    float cutoff;
    float outerCutOff;
    float intensity;
    int castShadow;
};

struct PointLight{
    vec3 position;
    vec3 color;

    float constant;
    float linear;
    float quadratic;
    float intensity;
};

struct DirectLight {
    vec3 direction;
    vec3 color;
    float intensity;
    int castShadow;
};

in vec2 TexCoords;
in vec3 Normal;
in vec4 FragPosLightSpace;
in vec3 tDirectLightPos[NR_DIRECT_LIGHTS];
in vec3 tPointLightPos[NR_POINT_LIGHTS];
in vec3 tSpotLightPos[NR_SPOT_LIGHTS];
in vec3 tViewPos;
in vec3 tFragPos;

uniform bool Has_normal_map;

uniform sampler2D mat_diffuse;
uniform sampler2D mat_specular;
uniform sampler2D mat_normal;
uniform sampler2D shadowMap;

uniform vec3 matDiffuse;
uniform vec3 matSpecular;
uniform float shininess;

uniform float far_plane;

uniform DirectLight directLights[NR_DIRECT_LIGHTS];
uniform PointLight pointLights[NR_POINT_LIGHTS];
uniform SpotLight spotLights[NR_SPOT_LIGHTS];

vec3 calcDirectLight(DirectLight,vec3,vec3,vec3,vec3);
vec3 calcPointLight(PointLight,vec3,vec3,vec3,vec3);
vec3 calcSpotLight(SpotLight,vec3,vec3,vec3,vec3);
float directShadowCalculation();

void main(){
    vec3 normal;
    if(Has_normal_map){
        normal=texture(mat_normal, TexCoords).rgb;
        normal = normalize(normal * 2.0 - 1.0);  // this normal is in tangent space
    }
    else
        normal=normalize(Normal);

    vec3 diffColor= matDiffuse+vec3(texture(mat_diffuse, TexCoords));   
    vec3 specColor= matSpecular+vec3(texture(mat_specular,TexCoords));

    vec3 result;
    result=vec3(0.0);
    for(int i = 0; i < NR_DIRECT_LIGHTS-2; i++)
        result += calcDirectLight(directLights[i],normal,tDirectLightPos[i],diffColor,specColor);
    for(int i = 0; i < NR_POINT_LIGHTS-2; i++)
        result += calcPointLight(pointLights[i],normal,tPointLightPos[i],vec3(0.0,0.2,0.4),specColor);
    for(int i = 0; i < NR_SPOT_LIGHTS-2; i++)
        result += calcSpotLight(spotLights[i],normal,tSpotLightPos[i],diffColor,specColor);
    vec4 color =vec4(result,1.0);   
    float gamma = 2.2;
    color.rgb = pow(color.rgb, vec3(1.0/gamma));
    vec4 ambient=vec4(0.2,0.2,0.2,1.0)*vec4(diffColor,1.0);
    glFragColor=ambient+color;
}

vec3 calcDirectLight(DirectLight light,vec3 norm,vec3 tLightPos,vec3 diffColor,vec3 specColor){ 
    vec3 lightDir ;
    if(Has_normal_map)
        lightDir= normalize(tLightPos);
    else
        lightDir = normalize(light.direction);

    float diff = max(dot(lightDir,norm), 0.0);
    vec3 diffuse = light.color * diff *diffColor;

    vec3 viewDir = normalize(tViewPos- tFragPos);       
    vec3 halfwayDir = normalize(lightDir + viewDir);
    float spec = pow(max(dot(norm, halfwayDir), 0.0), 32.0);
    vec3 specular = shininess* spec *specColor* light.color;
    vec3 result;
    if(light.castShadow==1){
        float shadow = directShadowCalculation();
        result =light.intensity* ( shadow* (diffuse + specular));
    }
    else
        result =light.intensity* (diffuse + specular);
    return result;
}

vec3 calcPointLight(PointLight light,vec3 norm,vec3 tLightPos,vec3 diffColor,vec3 specColor){
    vec3 lightDir ;
    if(Has_normal_map)
        lightDir= normalize(tLightPos-tFragPos);
    else
        lightDir = normalize(light.position - tFragPos);
    float diff = max(dot(lightDir,norm), 0.0);
    vec3 diffuse = light.color * diff * diffColor;

    vec3 viewDir = normalize(tViewPos- tFragPos);
    vec3 halfwayDir = normalize(lightDir + viewDir);
    float spec = pow(max(dot(norm, halfwayDir), 0.0), 16.0);        
    vec3 specular =shininess* specColor * spec * light.color;

    vec3 result;
    float distance = length(light.position - tFragPos);
    float attenuation = 1.0f / (light.constant + light.linear * distance +light.quadratic * (distance * distance));
    diffuse *= attenuation;
    specular *= attenuation;
    result=light.intensity*(diffuse+specular);
    return result;
}

vec3 calcSpotLight(SpotLight light,vec3 norm,vec3 tLightPos,vec3 diffColor,vec3 specColor){                   
    vec3 lightDir ;
    if(Has_normal_map)
        lightDir= normalize(tLightPos-tFragPos);
    else
        lightDir = normalize(light.position - tFragPos);
    float diff = max(dot(lightDir,norm), 0.0);
    vec3 diffuse = light.color * diff * diffColor;

    vec3 viewDir = normalize(tViewPos- tFragPos);

    float spec =0.0;
    vec3 halfwayDir = normalize(lightDir + viewDir);
    spec = pow(max(dot(norm, halfwayDir), 0.0), 16.0);    
    vec3 specular = shininess* light.color * spec * specColor;

    // Spotlight (soft edges)
    float theta = dot(lightDir, normalize(-light.direction)); 
    float epsilon = (light.cutoff - light.outerCutOff);
    float intensity = clamp((theta - light.outerCutOff) / epsilon, 0.0, 1.0);
    diffuse  *= intensity;
    specular *= intensity;

    // Attenuation
    float distance    = length(light.position - tFragPos);
    float attenuation = 1.0f / (light.constant + light.linear * distance + light.quadratic * (distance * distance));    
    diffuse  *= attenuation;
    specular *= attenuation;   

    vec3 result = intensity*(diffuse+specular);
    return result;
}

float directShadowCalculation(){
    vec3 projCoords = FragPosLightSpace.xyz / FragPosLightSpace.w;
    projCoords = projCoords * 0.5 + 0.5;
    float shadow = 1.0; 
    for (int i=0;i<4;i++){
        if ( texture( shadowMap, -projCoords.xy + poissonDisk[i]/700.0 ).z  <  -projCoords.z ){
           shadow-=0.2;
        }
    } 
    if(projCoords.z > 1.0)
        shadow = 0.0; 
    return shadow;
}

抱歉所有代码，但我不知道问题出在哪里，花了一周的时间搜索和调试，但没有任何进展。

编辑1- 灯光位置 vector 为 (-3.5f, 8.0f, 1.0f)2- 我将 directShadowCalculation() 更改为:

    float directShadowCalculation(){
    vec3 projCoords = FragPosLightSpace.xyz / FragPosLightSpace.w;
    projCoords = projCoords * 0.5 + 0.5;
    float shadow = 1.0; 
    for (int i=0;i<4;i++){
        if ( texture( shadowMap, projCoords.xy + poissonDisk[i]/700.0 ).z  <  projCoords.z ){
           shadow-=0.2;
        }
    } 
    if(projCoords.z > 1.0)
        shadow = 0.0; 
    return shadow;
}

这是结果

Answer 1

如果您必须将 View 空间坐标转换为光源的局部空间，则必须在执行操作时设置 lightSpaceMatrix:

lightSpaceMatrix = lightSpaceProjection * (lightSpaceView*camInv)

因为，您必须通过 camInv 从 View 空间转换到世界空间。然后，您必须转换从光源 (lightSpaceView) 看到的世界空间坐标。最后，您必须对其进行投影 lightSpaceProjection。

但是你在顶点着色器中直接从世界坐标转换到光源的局部空间:

FragPosLightSpace = lightSpaceMatrix * vec4(FragPos,1.0); 

因此，您必须像这样设置 lightSpaceMatrix:

lightSpaceMatrix = lightSpaceProjection * lightSpaceView

投影矩阵描述了从场景的 3D 点到视口(viewport)的 2D 点的映射。它从 View (眼睛)空间转换到剪辑空间，剪辑空间中的坐标通过除以剪辑坐标的 w 分量转换为归一化设备坐标 (NDC)。 NDC 的范围是 (-1,-1,-1) 到 (1,1,1)。这与正交投影或透视投影无关。

将投影片段位置(光空间)除以其 w 分量后，projCoords 的范围从 (-1, -1, -1) 到(1, 1, 1)。projCoords = projCoords * 0.5 + 0.5; 将 XY 坐标转换为纹理坐标，并将 Z 坐标转换为 [0, 1] 范围内的深度值。

vec3 projCoords = FragPosLightSpace.xyz / FragPosLightSpace.w;
projCoords = projCoords * 0.5 + 0.5;

阴影测试中的反转没有意义，因为纹理的内容也应该是 [0,1] 范围内的深度值。
影子测试应该看起来像这样:

if ( texture( shadowMap, projCoords.xy ).z < projCoords.z )
{
    ....
}

如果 sun->direction 是太阳的方向，那么 lightSpaceView 必须这样设置:

glm::mat4 lightSpaceView = glm::lookAt(sun->direction, glm::vec3(0, 0, 0), glm::vec3(0, 1, 0));

但是，如果 sun->direction 是太阳照射的方向，那么 lightSpaceView 必须这样设置:

glm::mat4 lightSpaceView = glm::lookAt(-sun->direction, glm::vec3(0, 0, 0), glm::vec3(0, 1, 0));

由于您对光使用正交投影并且光空间矩阵的原点靠近世界空间的原点，因此光投影的近平面应该在光空间的后面很远。否则，在生成光深度图时，靠近 太阳的物体将被光投影的近平面裁剪。

glm::mat4 lightSpaceProjection = glm::ortho(-40.0f, 40.0f, -40.0f, 40.0f, -100.0f, 100.0f);

由于光照计算是在 View 空间中完成的，因此您必须将光照位置从世界空间转换到 View 空间:

GLuint directLightPosLoc = glGetUniformLocation(phongShader.getProgramID(), (const GLchar*) ("directLightPos[" + ToString((*it)->index) + "]").c_str());
glm::vec3 dir = glm::mat3(camera->getViewMatrix()) * (*it)->direction;
glUniform3fv( directLightPosLoc, 1, &dir[0] );


GLuint pointLightPosLoc = glGetUniformLocation(phongShader.getProgramID(), (const GLchar*) ("pointLightPos[" + ToString((*it)->index) + "]").c_str());
glm::vec4 pos = camera->getViewMatrix( * glm::vec4((*it)->position.x, (*it)->position.y, (*it)->position.z, 1.0);
glUniform3fv( directLightPosLoc, 1, &pos[0] );


GLuint spotLightPosLoc = glGetUniformLocation(phongShader.getProgramID(), (const GLchar*) ("spotLightPos[" + ToString((*it)->index) + "]").c_str());
glm::vec4 pos = camera->getViewMatrix( * glm::vec4((*it)->position.x, (*it)->position.y, (*it)->position.z, 1.0);
glUniform3fv( spotLightPosLoc, 1, &pos[0] );

请参阅演示该算法的 WebGL 示例:

(function loadscene() {

var sliderScale = 100.0
var gl;
var progShadow;
var progDraw;
var shadowFB;
var bufTorus;
var bufGround;
var canvas;
var vp_size;
var fb_size;

function render(deltaMS){

var ambient = document.getElementById( "ambient" ).value / sliderScale;
var diffuse = document.getElementById( "diffuse" ).value / sliderScale;
var specular = document.getElementById( "specular" ).value / sliderScale;
var shininess = document.getElementById( "shininess" ).value;

canvas = document.getElementById( "scene-canvas" );

var lightPos = [-3.0, 0.0, 2.0];
var lightAnimationMat = RotateAxis( IdentityMat44(), CalcAng( deltaMS, 20.0 ), 2 );
lightPos = Transform( lightPos, lightAnimationMat );
var lightDir = [ -lightPos[0], -lightPos[1], -lightPos[2] ];
var light  = Camera.Create( lightPos, [0, 0, 0], [0, 0, 1], 110, [ 5.0, 5.0 ], -20.0, 20.0 );
var camera = Camera.Create( [0, 2.5, 2], [0, 0, 0], [0, 0, 1], 110, [vp_size[0], vp_size[1]], 0.5, 100.0 );

var lightPrjMat = Camera.Ortho( light );
var lightViewMat = Camera.LookAt( light );
var prjMat = Camera.Perspective( camera );
var viewMat = Camera.LookAt( camera );
var modelMat = IdentityMat44();
modelMat = RotateAxis( modelMat, CalcAng( deltaMS, 13.0 ), 0 );
modelMat = RotateAxis( modelMat, CalcAng( deltaMS, 17.0 ), 1 );
groundModelMat = IdentityMat44();
var viewLightDir = TransformVec( lightDir, viewMat );
    
gl.viewport( 0, 0, fb_size[0], fb_size[1] );
gl.enable( gl.DEPTH_TEST );

shadowFB.Bind( true );
ShaderProgram.Use( progShadow );
ShaderProgram.SetUniformM44( progShadow, "u_projectionMat44", lightPrjMat );
ShaderProgram.SetUniformM44( progShadow, "u_viewMat44", lightViewMat );
ShaderProgram.SetUniformM44( progShadow, "u_modelMat44", modelMat );
ShaderProgram.SetUniformF2( progShadow, "u_depthRange", [light.near, light.far] );

VertexBuffer.Draw( bufTorus );

gl.viewport( 0, 0, vp_size[0], vp_size[1] );
shadowFB.Release( true );
shadowFB.BindTexture( 1 );
ShaderProgram.Use( progDraw );
ShaderProgram.SetUniformM44( progDraw, "u_projectionMat44", prjMat );
ShaderProgram.SetUniformM44( progDraw, "u_viewMat44", viewMat );
ShaderProgram.SetUniformM44( progDraw, "u_lightProjectionMat44", lightPrjMat );
ShaderProgram.SetUniformM44( progDraw, "u_lightViewMat44", lightViewMat );
ShaderProgram.SetUniformM44( progDraw, "u_modelMat44", modelMat );
ShaderProgram.SetUniformI1( progDraw, "u_depthSampler", 1 );
ShaderProgram.SetUniformF3( progDraw, "u_lightDir", viewLightDir )
ShaderProgram.SetUniformF1( progDraw, "u_ambient", ambient )
ShaderProgram.SetUniformF1( progDraw, "u_diffuse", diffuse )
ShaderProgram.SetUniformF1( progDraw, "u_specular", specular )
ShaderProgram.SetUniformF1( progDraw, "u_shininess", shininess )

VertexBuffer.Draw( bufTorus );
ShaderProgram.SetUniformM44( progDraw, "u_modelMat44", groundModelMat );
VertexBuffer.Draw( bufGround );

requestAnimationFrame(render);
}

function nearestPow2( aSize ){
  return Math.pow( 2, Math.round( Math.log( aSize ) / Math.log( 2 ) ) ); 
}

function resize() {
    //vp_size = [gl.drawingBufferWidth, gl.drawingBufferHeight];
    vp_size = [window.innerWidth, window.innerHeight]
    canvas.width = vp_size[0];
    canvas.height = vp_size[1];

    var size = Math.max(256, Math.max(vp_size[0], vp_size[1]));
    size = nearestPow2(size/2);
    fb_size = [size, size]
    shadowFB = FrameBuffer.Create( fb_size ); 
}

function initScene() {

document.getElementById( "ambient" ).value = 0.2 * sliderScale;
document.getElementById( "diffuse" ).value = 0.7 * sliderScale;
document.getElementById( "specular" ).value = 0.5 * sliderScale;
document.getElementById( "shininess" ).value = 8.0;

canvas = document.getElementById( "scene-canvas");
vp_size = [canvas.width, canvas.height];
gl = canvas.getContext( "experimental-webgl" );
if ( !gl )
  return;

progShadow = ShaderProgram.Create( 
[ { source : "shadow-shader-vs", stage : gl.VERTEX_SHADER },
{ source : "shadow-shader-fs", stage : gl.FRAGMENT_SHADER }
] );
if (!progShadow.progObj)
    return null;
progShadow.inPos = ShaderProgram.AttributeIndex( progShadow, "inPos" );
progShadow.inNV  = ShaderProgram.AttributeIndex( progShadow, "inNV" );
progShadow.inCol = ShaderProgram.AttributeIndex( progShadow, "inCol" );

progDraw = ShaderProgram.Create( 
  [ { source : "draw-shader-vs", stage : gl.VERTEX_SHADER },
    { source : "draw-shader-fs", stage : gl.FRAGMENT_SHADER }
  ] );
if (!progDraw.progObj)
    return null;
progDraw.inPos = ShaderProgram.AttributeIndex( progDraw, "inPos" );
progDraw.inNV  = ShaderProgram.AttributeIndex( progDraw, "inNV" );
progDraw.inCol = ShaderProgram.AttributeIndex( progDraw, "inCol" );

// create torus
var circum_size = 32, tube_size = 32;
var rad_circum = 1.0;
var rad_tube = 0.5;
var torus_pts = [];
var torus_nv = [];
var torus_col = [];
var torus_inx = [];
var col = [1, 0.5, 0.0];
for ( var i_c = 0; i_c < circum_size; ++ i_c ) {
    var center = [
        Math.cos(2 * Math.PI * i_c / circum_size),
        Math.sin(2 * Math.PI * i_c / circum_size) ]
    for ( var i_t = 0; i_t < tube_size; ++ i_t ) {
        var tubeX = Math.cos(2 * Math.PI * i_t / tube_size)
        var tubeY = Math.sin(2 * Math.PI * i_t / tube_size)
        var pt = [
            center[0] * ( rad_circum + tubeX * rad_tube ),
            center[1] * ( rad_circum + tubeX * rad_tube ),
            tubeY * rad_tube ]
        var nv = [ pt[0] - center[0] * rad_tube, pt[1] - center[1] * rad_tube, tubeY * rad_tube ]
        torus_pts.push( pt[0], pt[1], pt[2] );
        torus_nv.push( nv[0], nv[1], nv[2] );
        torus_col.push( col[0], col[1], col[2] );
        var i_cn = (i_c+1) % circum_size
        var i_tn = (i_t+1) % tube_size
        var i_c0 = i_c * tube_size; 
        var i_c1 = i_cn * tube_size; 
        torus_inx.push( i_c0+i_t, i_c0+i_tn, i_c1+i_t, i_c0+i_tn, i_c1+i_t, i_c1+i_tn )
    }
}
bufTorus = VertexBuffer.Create(
  [ { data : torus_pts, attrSize : 3, attrLoc : progDraw.inPos },
    { data : torus_nv,  attrSize : 3, attrLoc : progDraw.inNV },
    { data : torus_col, attrSize : 3, attrLoc : progDraw.inCol } ],
    torus_inx
);

var g_l = 8.0;
var g_h = -2.5;
var g_c = [ 0.8, 0.6, 0.8 ];
bufGround = VertexBuffer.Create( 
    [ { data : [ -g_l, -g_l, g_h, g_l, -g_l, g_h, g_l, g_l, g_h, -g_l, g_l, g_h ], attrSize : 3, attrLoc : progDraw.inPos },
      { data : [ 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0 ], attrSize : 3, attrLoc : progDraw.inNV },
      { data : [ g_c[0], g_c[1], g_c[2], g_c[0], g_c[1], g_c[2], g_c[0], g_c[1], g_c[2], g_c[0], g_c[1], g_c[2] ], attrSize : 3, attrLoc : progDraw.inCol } ],
    [ 0, 1, 2, 0, 2, 3 ]
);

window.onresize = resize;
resize();
requestAnimationFrame(render);
}

var startTime;
function Fract( val ) { 
    return val - Math.trunc( val );
}
function CalcAng( deltaTime, intervall ) {
    return Fract( deltaTime / (1000*intervall) ) * 2.0 * Math.PI;
}

function IdentityMat44() { return [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1]; }

function RotateAxis(matA, angRad, axis) {
    var aMap = [ [1, 2], [2, 0], [0, 1] ];
    var a0 = aMap[axis][0], a1 = aMap[axis][1]; 
    var sinAng = Math.sin(angRad), cosAng = Math.cos(angRad);
    var matB = IdentityMat44();
    for ( var i = 0; i < 16; ++ i ) matB[i] = matA[i];
    for ( var i = 0; i < 3; ++ i ) {
        matB[a0*4+i] = matA[a0*4+i] * cosAng + matA[a1*4+i] * sinAng;
        matB[a1*4+i] = matA[a0*4+i] * -sinAng + matA[a1*4+i] * cosAng;
    }
    return matB;
}

function Cross( a, b ) { return [ a[1] * b[2] - a[2] * b[1], a[2] * b[0] - a[0] * b[2], a[0] * b[1] - a[1] * b[0], 0.0 ]; }
function Dot( a, b ) { return a[0]*b[0] + a[1]*b[1] + a[2]*b[2]; }
function Normalize( v ) {
    var len = Math.sqrt( v[0] * v[0] + v[1] * v[1] + v[2] * v[2] );
    return [ v[0] / len, v[1] / len, v[2] / len ];
}

Transform = function(vec, mat) {
    return [
        vec[0] * mat[0*4+0] + vec[1] * mat[1*4+0] + vec[2] * mat[2*4+0] + mat[3*4+0],
        vec[0] * mat[0*4+1] + vec[1] * mat[1*4+1] + vec[2] * mat[2*4+1] + mat[3*4+1],
        vec[0] * mat[0*4+2] + vec[1] * mat[1*4+2] + vec[2] * mat[2*4+2] + mat[3*4+2],
        vec[0] * mat[0*4+3] + vec[1] * mat[1*4+3] + vec[2] * mat[2*4+3] + mat[3*4+3] ]
    if ( h[3] == 0.0 )
        return [0, 0, 0]
    return [ h[0]/h[3], h[1]/h[3], h[2]/h[3] ];
}

TransformVec = function(vec, mat) {
   return [
        vec[0] * mat[0*4+0] + vec[1] * mat[1*4+0] + vec[2] * mat[2*4+0],
        vec[0] * mat[0*4+1] + vec[1] * mat[1*4+1] + vec[2] * mat[2*4+1],
        vec[0] * mat[0*4+2] + vec[1] * mat[1*4+2] + vec[2] * mat[2*4+2] ]
}

var Camera = {};
Camera.Create = function( pos, target, up, fov_y, vp, near, far ) {
    var camera = {};
    camera.pos    = pos;
    camera.target = target;
    camera.up     = up;
    camera.fov_y  = fov_y;
    camera.vp     = vp;
    camera.near   = near;
    camera.far    = far;
    return camera;
}
Camera.Ortho = function( camera ) {
    var fn = camera.far + camera.near;
    var f_n = camera.far - camera.near;
    var w = camera.vp[0];
    var h = camera.vp[1];
    var m = IdentityMat44();
    m[0]  = 2 / w; m[1]  = 0;     m[2]  =  0;        m[3]  = 0;
    m[4]  = 0;     m[5]  = 2 / h; m[6]  =  0;        m[7]  = 0;
    m[8]  = 0;     m[9]  = 0;     m[10] = -2 / f_n;  m[11] = 0;
    m[12] = 0;     m[13] = 0;     m[14] = -fn / f_n; m[15] = 1;
    return m;
}
Camera.Perspective = function( camera ) {
    var fn = camera.far + camera.near;
    var f_n = camera.far - camera.near;
    var r = camera.vp[0] / camera.vp[1];
    var t = 1 / Math.tan( Math.PI * camera.fov_y / 360 );
    var m = IdentityMat44();
    m[0]  = t/r; m[1]  = 0; m[2]  =  0;                              m[3]  = 0;
    m[4]  = 0;   m[5]  = t; m[6]  =  0;                              m[7]  = 0;
    m[8]  = 0;   m[9]  = 0; m[10] = -fn / f_n;                       m[11] = -1;
    m[12] = 0;   m[13] = 0; m[14] = -2 * camera.far * camera.near / f_n; m[15] =  0;
    return m;
}
Camera.LookAt = function( camera ) {
    var mz = Normalize( [ camera.pos[0]-camera.target[0], camera.pos[1]-camera.target[1], camera.pos[2]-camera.target[2] ] );
    var mx = Normalize( Cross( camera.up, mz ) );
    var my = Normalize( Cross( mz, mx ) );
    var tx = Dot( mx, camera.pos );
    var ty = Dot( my, camera.pos );
    var tz = Dot( [-mz[0], -mz[1], -mz[2]], camera.pos ); 
    var m = IdentityMat44();
    m[0]  = mx[0]; m[1]  = my[0]; m[2]  = mz[0]; m[3]  = 0;
    m[4]  = mx[1]; m[5]  = my[1]; m[6]  = mz[1]; m[7]  = 0;
    m[8]  = mx[2]; m[9]  = my[2]; m[10] = mz[2]; m[11] = 0;
    m[12] = tx;    m[13] = ty;    m[14] = tz;    m[15] = 1; 
    return m;
} 

var ShaderProgram = {};
ShaderProgram.Create = function (shaderList) {
    var shaderObjs = [];
    for (var i_sh = 0; i_sh < shaderList.length; ++i_sh) {
        var shderObj = this.CompileShader(shaderList[i_sh].source, shaderList[i_sh].stage);
        if (shderObj == 0)
            return 0;
        shaderObjs.push(shderObj);
    }
    var prog = {}
    prog.progObj = this.LinkProgram(shaderObjs)
    if (prog.progObj) {
        prog.attribIndex = {};
        var noOfAttributes = gl.getProgramParameter(prog.progObj, gl.ACTIVE_ATTRIBUTES);
        for (var i_n = 0; i_n < noOfAttributes; ++i_n) {
            var name = gl.getActiveAttrib(prog.progObj, i_n).name;
            prog.attribIndex[name] = gl.getAttribLocation(prog.progObj, name);
        }
        prog.unifomLocation = {};
        var noOfUniforms = gl.getProgramParameter(prog.progObj, gl.ACTIVE_UNIFORMS);
        for (var i_n = 0; i_n < noOfUniforms; ++i_n) {
            var name = gl.getActiveUniform(prog.progObj, i_n).name;
            prog.unifomLocation[name] = gl.getUniformLocation(prog.progObj, name);
        }
    }
    return prog;
}
ShaderProgram.AttributeIndex = function (prog, name) { return prog.attribIndex[name]; }
ShaderProgram.UniformLocation = function (prog, name) { return prog.unifomLocation[name]; }
ShaderProgram.Use = function (prog) { gl.useProgram(prog.progObj); }
ShaderProgram.SetUniformI1 = function (prog, name, val) { if (prog.unifomLocation[name]) gl.uniform1i(prog.unifomLocation[name], val); }
ShaderProgram.SetUniformF1 = function (prog, name, val) { if (prog.unifomLocation[name]) gl.uniform1f(prog.unifomLocation[name], val); }
ShaderProgram.SetUniformF2 = function (prog, name, arr) { if (prog.unifomLocation[name]) gl.uniform2fv(prog.unifomLocation[name], arr); }
ShaderProgram.SetUniformF3 = function (prog, name, arr) { if (prog.unifomLocation[name]) gl.uniform3fv(prog.unifomLocation[name], arr); }
ShaderProgram.SetUniformF4 = function (prog, name, arr) { if (prog.unifomLocation[name]) gl.uniform4fv(prog.unifomLocation[name], arr); }
ShaderProgram.SetUniformM33 = function (prog, name, mat) { if (prog.unifomLocation[name]) gl.uniformMatrix3fv(prog.unifomLocation[name], false, mat); }
ShaderProgram.SetUniformM44 = function (prog, name, mat) { if (prog.unifomLocation[name]) gl.uniformMatrix4fv(prog.unifomLocation[name], false, mat); }
ShaderProgram.CompileShader = function (source, shaderStage) {
    var shaderScript = document.getElementById(source);
    if (shaderScript)
        source = shaderScript.text;
    var shaderObj = gl.createShader(shaderStage);
    gl.shaderSource(shaderObj, source);
    gl.compileShader(shaderObj);
    var status = gl.getShaderParameter(shaderObj, gl.COMPILE_STATUS);
    if (!status) alert(gl.getShaderInfoLog(shaderObj));
    return status ? shaderObj : null;
}
ShaderProgram.LinkProgram = function (shaderObjs) {
    var prog = gl.createProgram();
    for (var i_sh = 0; i_sh < shaderObjs.length; ++i_sh)
        gl.attachShader(prog, shaderObjs[i_sh]);
    gl.linkProgram(prog);
    status = gl.getProgramParameter(prog, gl.LINK_STATUS);
    if (!status) alert("Could not initialise shaders");
    gl.useProgram(null);
    return status ? prog : null;
}

var VertexBuffer = {};
VertexBuffer.Create = function( attributes, indices ) {
    var buffer = {};
    buffer.buf = [];
    buffer.attr = []
    for ( var i = 0; i < attributes.length; ++ i ) {
        buffer.buf.push( gl.createBuffer() );
        buffer.attr.push( { size : attributes[i].attrSize, loc : attributes[i].attrLoc } );
        gl.bindBuffer( gl.ARRAY_BUFFER, buffer.buf[i] );
        gl.bufferData( gl.ARRAY_BUFFER, new Float32Array( attributes[i].data ), gl.STATIC_DRAW );
    }
    buffer.inx = gl.createBuffer();
    gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, buffer.inx );
    gl.bufferData( gl.ELEMENT_ARRAY_BUFFER, new Uint16Array( indices ), gl.STATIC_DRAW );
    buffer.inxLen = indices.length;
    gl.bindBuffer( gl.ARRAY_BUFFER, null );
    gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, null );
    return buffer;
}
VertexBuffer.Draw = function( bufObj ) {
  for ( var i = 0; i < bufObj.buf.length; ++ i ) {
        gl.bindBuffer( gl.ARRAY_BUFFER, bufObj.buf[i] );
        gl.vertexAttribPointer( bufObj.attr[i].loc, bufObj.attr[i].size, gl.FLOAT, false, 0, 0 );
        gl.enableVertexAttribArray( bufObj.attr[i].loc );
    }
    gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufObj.inx );
    gl.drawElements( gl.TRIANGLES, bufObj.inxLen, gl.UNSIGNED_SHORT, 0 );
    for ( var i = 0; i < bufObj.buf.length; ++ i )
       gl.disableVertexAttribArray( bufObj.attr[i].loc );
    gl.bindBuffer( gl.ARRAY_BUFFER, null );
    gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, null );
}

var FrameBuffer = {};
FrameBuffer.Create = function( vp, texturePlan ) {
    var texPlan = texturePlan ? new Uint8Array( texturePlan ) : null;
    var fb = gl.createFramebuffer();
    var fbsize = Math.max(vp[0], vp[1]);
    fbsize = 1 << 31 - Math.clz32(fbsize); // nearest power of 2
    fb.width = fbsize;
    fb.height = fbsize;
    gl.bindFramebuffer( gl.FRAMEBUFFER, fb );
    fb.color0_texture = gl.createTexture();
    gl.bindTexture( gl.TEXTURE_2D, fb.color0_texture );
    gl.texImage2D( gl.TEXTURE_2D, 0, gl.RGBA, fb.width, fb.height, 0, gl.RGBA, gl.UNSIGNED_BYTE, texPlan );
    gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST );
    gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST );
    gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE );
    gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE );
    fb.renderbuffer = gl.createRenderbuffer();
    gl.bindRenderbuffer( gl.RENDERBUFFER, fb.renderbuffer );
    gl.renderbufferStorage( gl.RENDERBUFFER, gl.DEPTH_COMPONENT16, fb.width, fb.height );
    gl.framebufferTexture2D( gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, fb.color0_texture, 0 );
    gl.framebufferRenderbuffer( gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, fb.renderbuffer );
    gl.bindTexture( gl.TEXTURE_2D, null );
    gl.bindRenderbuffer( gl.RENDERBUFFER, null );
    gl.bindFramebuffer( gl.FRAMEBUFFER, null );

    fb.Bind = function( clear ) {
        gl.bindFramebuffer( gl.FRAMEBUFFER, this );
        if ( clear ) {
            gl.clearColor( 0.0, 0.0, 0.0, 1.0 );
            gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );
        }
    };

    fb.Release = function( clear ) {
        gl.bindFramebuffer( gl.FRAMEBUFFER, null );
        if ( clear ) {
            gl.clearColor( 0.0, 0.0, 0.0, 1.0 );
            gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );
        }
    };

    fb.BindTexture = function( textureUnit ) {
        gl.activeTexture( gl.TEXTURE0 + textureUnit );
        gl.bindTexture( gl.TEXTURE_2D, this.color0_texture );
    };

    return fb;
}

initScene();
  
})();

html,body {
    height: 100%;
    width: 100%;
    margin: 0;
    overflow: hidden;
}

#gui {
    position : absolute;
    top : 0;
    left : 0;
}

<script id="shadow-shader-vs" type="x-shader/x-vertex">
  precision mediump float;
  
  attribute vec3 inPos;
  attribute vec3 inNV;
  attribute vec3 inCol;
  
  varying vec3 vertPos;
  varying vec3 vertNV;
  varying vec3 vertCol;
  varying vec4 vPosPrj;
  
  uniform mat4 u_projectionMat44;
  uniform mat4 u_viewMat44;
  uniform mat4 u_modelMat44;
  
  void main()
  {
      vec3 modelNV  = mat3( u_modelMat44 ) * normalize( inNV );
      vertNV        = mat3( u_viewMat44 ) * modelNV;
      vertCol       = inCol;
      vec4 modelPos = u_modelMat44 * vec4( inPos, 1.0 );
      vec4 viewPos  = u_viewMat44 * modelPos;
      vertPos       = viewPos.xyz / viewPos.w;
      vPosPrj       = u_projectionMat44 * viewPos;
      gl_Position   = vPosPrj;
  }
</script>

<script id="shadow-shader-fs" type="x-shader/x-fragment">
    precision mediump float;
    
    varying vec3 vertPos;
    varying vec3 vertNV;
    varying vec3 vertCol;
    varying vec4 vPosPrj;

    uniform vec2 u_depthRange;

    vec3 PackDepth( in float depth )
    {
        float depthVal = depth * (256.0*256.0*256.0 - 1.0) / (256.0*256.0*256.0);
        vec4 encode = fract( depthVal * vec4(1.0, 256.0, 256.0*256.0, 256.0*256.0*256.0) );
        return encode.xyz - encode.yzw / 256.0 + 1.0/512.0;
    }
    
    void main()
    {
        float ndc_depth = vPosPrj.z / vPosPrj.w;
        float nearZ     = u_depthRange.x;
        float farZ      = u_depthRange.y;
        float depth     = ndc_depth * 0.5 + 0.5;
        gl_FragColor    = vec4( PackDepth( depth ).xyz, 1.0 );
    }
</script>

<script id="draw-shader-vs" type="x-shader/x-vertex">
precision mediump float;

attribute vec3 inPos;
attribute vec3 inNV;
attribute vec3 inCol;

varying vec3 vertPos;
varying vec3 vertNV;
varying vec3 vertCol;
varying vec4 lightPrj;
varying vec4 vPosPrj;

uniform mat4 u_projectionMat44;
uniform mat4 u_viewMat44;
uniform mat4 u_modelMat44;
uniform mat4 u_lightProjectionMat44;
uniform mat4 u_lightViewMat44;

void main()
{
    vec3 modelNV  = mat3( u_modelMat44 ) * normalize( inNV );
    vertNV        = mat3( u_viewMat44 ) * modelNV;
    vertCol       = inCol;
    vec4 modelPos = u_modelMat44 * vec4( inPos, 1.0 );
    vec4 lightPos = u_lightViewMat44 * modelPos;
    vec4 viewPos  = u_viewMat44 * modelPos;
    lightPrj      = u_lightProjectionMat44 * lightPos;
    vertPos       = viewPos.xyz / viewPos.w;
    vPosPrj       = u_projectionMat44 * viewPos;
    gl_Position   = vPosPrj;
}
</script>
  
<script id="draw-shader-fs" type="x-shader/x-fragment">
precision mediump float;

varying vec3 vertPos;
varying vec3 vertNV;
varying vec3 vertCol;
varying vec4 lightPrj;
varying vec4 vPosPrj;

uniform sampler2D u_depthSampler;
uniform vec3      u_lightDir;
uniform float     u_ambient;
uniform float     u_diffuse;
uniform float     u_specular;
uniform float     u_shininess;

float UnpackDepth( in vec3 pack )
{
  float depth = dot( pack, 1.0 / vec3(1.0, 256.0, 256.0*256.0) );
  return depth * (256.0*256.0*256.0) / (256.0*256.0*256.0 - 1.0);
}

float Depth( in sampler2D depthSampler, in vec2 texC )
{
  vec3 depthVal = texture2D( depthSampler, texC.st ).xyz;  
  return UnpackDepth( depthVal.rgb );
}

void main()
{
    vec3  ndc_light  = lightPrj.xyz / lightPrj.w;
    vec2  lightTexC  = ndc_light.xy * 0.5 + 0.5;
    float lightDepth = ndc_light.z * 0.5 + 0.5;
    float testDepth  = Depth( u_depthSampler, lightTexC );
    float shadow     = step( lightDepth-0.01, testDepth ) + step( testDepth, 0.0 );
    vec3  color      = vertCol;
    vec3  lightCol   = u_ambient * color;
    vec3  normalV    = normalize( vertNV );
    vec3  lightV     = normalize( -u_lightDir );
    float NdotL      = max( 0.0, dot( normalV, lightV ) );
    lightCol        += shadow * NdotL * u_diffuse * color;
    vec3  eyeV       = normalize( -vertPos );
    vec3  halfV      = normalize( eyeV + lightV );
    float NdotH      = max( 0.0, dot( normalV, halfV ) );
    float kSpecular  = ( u_shininess + 2.0 ) * pow( NdotH, u_shininess ) / ( 2.0 * 3.14159265 );
    lightCol        += shadow * kSpecular * u_specular * color;
    gl_FragColor     = vec4( lightCol.rgb, 1.0 );
}
</script>

<div><form id="gui" name="inputs"><table>
    <tr> <td> <font color= #CCF>ambient</font> </td> 
            <td> <input type="range" id="ambient" min="0" max="100" value="0"/></td> </tr>
    <tr> <td> <font color= #CCF>diffuse</font> </td> 
            <td> <input type="range" id="diffuse" min="0" max="100" value="0"/></td> </tr>
    <tr> <td> <font color= #CCF>specular</font> </td> 
            <td> <input type="range" id="specular" min="0" max="100" value="0"/></td> </tr>
    <tr> <td> <font color= #CCF>shininess</font> </td> 
            <td> <input type="range" id="shininess" min="0" max="100" value="0"/></td> </tr>
</table></form></div>

<canvas id="scene-canvas" style="border: none;" width="512" height="512"></canvas>

另见

• How to render depth linearly in modern OpenGL with gl_FragCoord.z in fragment shader
• Transform the modelMatrix