溶解(Dissolve)效果

最新推荐文章于 2023-12-27 23:07:19 发布

JettHuang

最新推荐文章于 2023-12-27 23:07:19 发布

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分类专栏： OpenGL + ShaderLanguage 文章标签： float vector

本文链接：https://blog.youkuaiyun.com/huangzhipeng/article/details/7956656

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本文深入解析了顶点着色与片段着色的实现过程，包括顶点着色器如何处理顶点数据，以及片段着色器如何进行光线与表面交互的计算。同时介绍了使用discard指令来优化渲染性能，以及纹理图片如何影响最终渲染结果。

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顶点着色, 正常处理顶点


// ADS Point lighting Shader
// Vertex Shader
// Richard S. Wright Jr.
// OpenGL SuperBible
#version 130

// Incoming per vertex... position and normal
in vec4 vVertex;
in vec3 vNormal;
in vec2 vTexCoords0;


uniform mat4   mvpMatrix;
uniform mat4   mvMatrix;
uniform mat3   normalMatrix;
uniform vec3   vLightPosition;

// Color to fragment program
smooth out vec3 vVaryingNormal;
smooth out vec3 vVaryingLightDir;
smooth out vec2 vVaryingTexCoord;


void main(void) 
    {
    // Pass on the texture coordinates 
    vVaryingTexCoord = vTexCoords0;

    // Get surface normal in eye coordinates
    vVaryingNormal = normalMatrix * vNormal;

    // Get vertex position in eye coordinates
    vec4 vPosition4 = mvMatrix * vVertex;
    vec3 vPosition3 = vPosition4.xyz / vPosition4.w;

    // Get vector to light source
    vVaryingLightDir = normalize(vLightPosition - vPosition3);


    // Don't forget to transform the geometry!
    gl_Position = mvpMatrix * vVertex;
    }

片断着色：discard指令

// ADS Point lighting Shader
// Fragment Shader
// Richard S. Wright Jr.
// OpenGL SuperBible
#version 130

out vec4 vFragColor;

uniform vec4       ambientColor;
uniform vec4       diffuseColor;   
uniform vec4       specularColor;
uniform sampler2D  cloudTexture;           // 存放dissvole纹理
uniform float      dissolveFactor;         // 每帧都变化的阈值

smooth in vec3 vVaryingNormal;
smooth in vec3 vVaryingLightDir;
smooth in vec2 vVaryingTexCoord;

void main(void)
    { 
    vec4 vCloudSample = texture(cloudTexture, vVaryingTexCoord);

    if(vCloudSample.r < dissolveFactor)
        discard;         // 如果小于阈值，就抛弃该片断


    // Dot product gives us diffuse intensity
    float diff = max(0.0, dot(normalize(vVaryingNormal), normalize(vVaryingLightDir)));

    // Multiply intensity by diffuse color, force alpha to 1.0
    vFragColor = diff * diffuseColor;

    // Add in ambient light
    vFragColor += ambientColor;


    // Specular Light
    vec3 vReflection = normalize(reflect(-normalize(vVaryingLightDir), normalize(vVaryingNormal)));
    float spec = max(0.0, dot(normalize(vVaryingNormal), vReflection));
    if(diff != 0) {
        float fSpec = pow(spec, 128.0);
        vFragColor.rgb += vec3(fSpec, fSpec, fSpec);
        }
    }

纹理图片：

运行效果截图：