Open GL ES着色器 - 获取属性

Question

我使用以下代码尝试从我的着色器中检索属性。

这段代码是检索制服而不是属性。

/*********** Get attribute locations. ***************/ 
// Dictionary to store each active attribute 
NSMutableDictionary *m_attributes = [[NSMutableDictionary alloc] init]; 
int m_nAttributes = -1; 
glGetProgramiv(_program, GL_ACTIVE_ATTRIBUTES, &m_nAttributes); 

for(GLuint i = 0; i < m_nAttributes; i++) { 
    int name_len=-1, num=-1; 
    GLenum type = GL_ZERO; 
    char attributesName[100]; 

    glGetActiveUniform(_program, i, sizeof(attributesName)-1, &name_len, &num, &type, attributesName); 

    attributesName[name_len] = 0; 

    GLuint attributes = glGetUniformLocation(_program, attributesName); 

    [m_attributes setObject:[NSNumber numberWithUnsignedInt:attributes] 
        forKey:[NSString stringWithUTF8String:attributesName]];   
} 

这里是我的着色器：

attribute vec3 VertexPosition; 
attribute vec3 VertexNormal; 
attribute vec2 VertexTexCoord0; 


uniform mat4 ModelViewMatrix; 
uniform mat4 ModelViewProjMatrix; 


varying vec3 Normal; 
varying vec2 TexCoord0; 


void main(void) 
{ 
    Normal = VertexNormal; 
     TexCoord0 = VertexTexCoord0; 

    gl_Position = ModelViewProjMatrix * vec4(VertexPosition, 1.0); 
} 

有人能看到anythng我做错了吗？

Answer 1

您应该使用glGetActiveAttrib而不是glGetActiveUniform和glGetAttribLocation来获取属性索引而不是glGetUniformLocation。

也得到了属性名称的最大长度分配由glGetActiveAttrib需要，而不是硬编码char attributesName[100];

GLint maxNameLength; 
glGetProgramiv(program_handle, GL_ACTIVE_ATTRIBUTE_MAX_LENGTH, &maxNameLength);