쉐이더(Shader) 객체

처리과정

//------------------------------------------------------------------------------

// 1. shader 생성

//------------------------------------------------------------------------------

vertex shader 생성

GLuint vertShader; // 쉐이더객체의 핸들

vertShader = glCreateShader(GL_VERTEX_SHADER); 

fragment shader 생성

GLuint fragShader; // 쉐이더객체의 핸들

fragShader = glCreateShader(GL_FRAGMENT_SHADER);

//------------------------------------------------------------------------------

// 2. 생성된 쉐이더에 소스코드를 적재한다.

//------------------------------------------------------------------------------

const GLchar* sourceVertShader;

const GLchar* sourceFragShader;

sourceVertShader = (GLchar*)[[NSString stringWithContentsOfFile:file1 encoding:NSUTF8StringEncoding error:nil] UTF8String];

sourceFragShader = (GLchar*)[[NSString stringWithContentsOfFile:file2 encoding:NSUTF8StringEncoding error:nil] UTF8String];

glShaderSource(vertShader, 1, &sourceVertShader, NULL);

glShaderSource(fragShader, 1, &sourceFragShader, NULL);

   

//------------------------------------------------------------------------------

// 3. 쉐이더를 컴파일한다

//------------------------------------------------------------------------------

glCompileShader(vertShader);

glCompileShader(fragShader);

//------------------------------------------------------------------------------

// 4. 컴파일 결과를 확인한다.

//------------------------------------------------------------------------------

GLint status;

glGetShaderiv(vertShader, GL_COMPILE_STATUS, status);

if(status != GL_TRUE)

{

  glDeleteShader(vertShader);

  return;

}

   

glGetShaderiv(fragShader, GL_COMPILE_STATUS, status);

if(status != GL_TRUE)

{

  glDeleteShader(fragShader);

  return;

}

//------------------------------------------------------------------------------

// 쉐이더 컴파일 에러날때 에러내용 보기

//------------------------------------------------------------------------------

GLint logLength;

glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &logLength);

if (logLength > 0)

{

  GLchar *log = (GLchar*)malloc(logLength);

  glGetShaderInfoLog(*shader, logLength, &logLength, log);

  NSLog(@"Shader compile log:\n%s", log);

  free(log);

}

//------------------------------------------------------------------------------

// 함수 원형

//------------------------------------------------------------------------------

GLuint glCreateShader(GLenum type);

GLuint glDeleteShader(GLuint shader); // 즉시 삭제하지 않는다. 참조가 없어지면 해제됨

void glShaderSource(GLuint shader, GLsizei count, const char** string, const GLint* length);

void glCompileShader(GLuint shader);

void glGetShaderiv(GLuint shader, GLenum pname, GLint *params);