Question

我基本上是在OpenTK中尝试Specular Lighting（OpenGL的c＃实现），我设法让Ambient和Diffuse照明工作，但是现在我对GL.getUniformLocation的调用返回-1并带有镜面矢量值（和我不确定“光泽”是否正确初始化。我已经研究了关于gl.getUniformLocation的OpenTK和OpenGL的许多类型的文档，以及为什么它有时会返回一个负值，并且我“几乎”确定我正确使用了镜面均匀值。

为清楚起见，以下是使用Microsoft Visual Studio 2010的解决方案中的代码：

Vector3 lightDirection = new Vector3(0.1f, 0.0f, 0.0f);
Vector3 ambientIllumination = new Vector3(0.3f, 0.3f, 0.3f);
Vector3 ambientReflection = new Vector3(0.3f, 0.3f, 0.3f);
Vector3 diffuseIllumination = new Vector3(0.7f, 0.7f, 0.7f);
Vector3 diffuseReflection = new Vector3(0.7f, 0.7f, 0.7f);
Vector3 specularIllumination = new Vector3(0.5f, 0.5f, 0.5f);
Vector3 specularReflection = new Vector3(0.5f, 0.5f, 0.5f);
float shininess = 0.5f;

int lightDirectionLocation = GL.GetUniformLocation(shaderProgramID, "lightDirection");
GL.Uniform3(lightDirectionLocation, ref lightDirection);

int ambientIlluminationLocation = GL.GetUniformLocation(shaderProgramID, "ambientIllumination");
GL.Uniform3(ambientIlluminationLocation, ref ambientIllumination);

int ambientReflectionLocation = GL.GetUniformLocation(shaderProgramID, "ambientReflection");
GL.Uniform3(ambientReflectionLocation, ref ambientReflection);            

int diffuseIlluminationLocation = GL.GetUniformLocation(shaderProgramID, "diffuseIllumination");
GL.Uniform3(diffuseIlluminationLocation, ref diffuseIllumination);

int diffuseReflectionLocation = GL.GetUniformLocation(shaderProgramID, "diffuseReflection");
GL.Uniform3(diffuseReflectionLocation, ref diffuseReflection);

int specularIlluminationLocation = GL.GetUniformLocation(shaderProgramID, "specularIllumination");
GL.Uniform3(specularIlluminationLocation, ref specularIllumination);

int specularReflectionLocation = GL.GetUniformLocation(shaderProgramID, "specularReflection");
GL.Uniform3(specularReflectionLocation, ref specularReflection);

int shininessLocation = GL.GetUniformLocation(shaderProgramID, "shininess");
GL.Uniform1(shininessLocation, shininess);

我正在使用的着色器代码：

#version 150

uniform mat4 viewMatrix;
uniform mat4 modelMatrix;
uniform mat4 projMatrix;

// Light properties
uniform vec3 ambientIllumination;
uniform vec3 diffuseIllumination;
uniform vec3 specularIllumination;
uniform vec3 lightDirection;

// Material properties
uniform vec3 ambientReflection;
uniform vec3 diffuseReflection;
uniform vec3 specularReflection;

uniform float shininess;

in vec3 position;
in vec3 normal;

out vec3 Colour;

void main()
{
    vec3 transformedNormal = normalize(vec3(viewMatrix * modelMatrix * vec4(normal, 0.0)));
    vec3 surfaceToLight = normalize(vec3(viewMatrix * vec4(-lightDirection, 0.0)));
    Colour = ambientIllumination * ambientReflection;
    float normalDotLight = dot(transformedNormal, surfaceToLight);
    if(normalDotLight > 0.0)
    {
        vec3 surfaceToEye = normalize(vec3(viewMatrix * modelMatrix * vec4(position, 1.0)));
        Colour += specularIllumination * specularReflection * pow(max(dot(reflect(surfaceToLight, transformedNormal), surfaceToEye), 0.0), shininess);
        Colour += diffuseIllumination * diffuseReflection * normalDotLight;
    }
    gl_Position = projMatrix * viewMatrix * modelMatrix * vec4(position, 1);
}

Answer 1

GL.getUniformLocation在找不到统一变量时返回-1。即使您在着色器中列出变量，编译器也许可以对其进行优化。

您没有显示片段着色器，但如果您不在片段着色器中使用Color，则整个计算将被优化，包括您定义的制服。在这些情况下，GL.getUniformLocation也将返回-1。

GL.getUniformLocation镜面光照返回负值

1 个答案: