GLSL示例不能在mac上工作
问题描述:
我想在Mac上创建一个GLSL示例。我试图为每个顶点设置一个颜色属性。但是,当程序运行时,我只会看到一个紫色屏幕(紫色来自glClearColor)。我发布了相关的代码片段。GLSL示例不能在mac上工作
-(void)drawRect:(NSRect)dirtyRect
{
// get program ID for shader program
GLuint programID = [self loadShaders];
// get new dimensions
NSSize dim = [self frame].size;
// clear the background with color
glClearColor(0.4f, 0.1f, 0.7f, 1.0f);
glDepthRange(1.0, -1.0);
glViewport(0, 0, dim.width, dim.height);
glClear(GL_COLOR_BUFFER_BIT);
// generate a buffer for our triangle
glGenBuffers(2, vertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer[0]);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer[1]);
glBufferData(GL_ARRAY_BUFFER, sizeof(colors), colors, GL_STATIC_DRAW);
glUseProgram(programID);
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer[0]);
glEnableVertexAttribArray(0);
glVertexAttribPointer(VERTEX_POS_INDEX, VERTEX_POS_SIZE, GL_FLOAT, GL_FALSE, VERTEX_POS_SIZE*sizeof(vertices), vertices);
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer[1]);
glEnableVertexAttribArray(1);
glVertexAttribPointer(VERTEX_COLOR_INDEX, VERTEX_COLOR_SIZE, GL_FLOAT, GL_FALSE, VERTEX_POS_SIZE*sizeof(colors), colors);
glDrawArrays(GL_TRIANGLES, 0, 3);
glDisableVertexAttribArray(0);
glDisableVertexAttribArray(1);
glUseProgram(0);
// flush buffer
glFlush();
[[self openGLContext] flushBuffer];
}
然后加载阴影代码:
-(GLuint)loadShaders
{
printf("GLSL version %s\n", glGetString(GL_SHADING_LANGUAGE_VERSION));
printf("GL Version: %s", glGetString(GL_VERSION));
// Create the shaders
GLuint vertexShaderID = glCreateShader(GL_VERTEX_SHADER);
GLuint fragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);
// get handle for app bundle
NSBundle *appBundle = [NSBundle mainBundle];
// get the path for the vertex shader file
NSString *vertexFilePath = [appBundle pathForResource:vertexShaderFile ofType:nil];
// get the path for the fragment shader file
NSString *fragmentFilePath = [appBundle pathForResource:fragmentShaderFile ofType:nil];
// get the contents of the vertex shader file into a string
NSString *vertexFileContents = [NSString stringWithContentsOfFile:vertexFilePath encoding:NSUTF8StringEncoding error:NULL];
NSLog(@"%@", vertexFileContents);
// get the contents of the fragment shader file into a string
NSString *fragmentFileContents = [NSString stringWithContentsOfFile:fragmentFilePath encoding:NSUTF8StringEncoding error:NULL];
NSLog(@"%@", fragmentFileContents);
GLint Result = GL_FALSE;
int infoLogLength;
// get a pointer the vertex shader program source, compile shader program
const char *vertexSourcePointer = [vertexFileContents UTF8String];
glShaderSource(vertexShaderID, 1, &vertexSourcePointer, NULL);
glCompileShader(vertexShaderID);
// check the vertex shader
glGetShaderiv(vertexShaderID, GL_COMPILE_STATUS, &Result);
glGetShaderiv(vertexShaderID, GL_INFO_LOG_LENGTH, &infoLogLength);
char vertexShaderErrorMessage[infoLogLength];
glGetShaderInfoLog(vertexShaderID, infoLogLength, NULL, vertexShaderErrorMessage);
// print error message
NSLog(@"%@", [NSString stringWithUTF8String:vertexShaderErrorMessage]);
// get a pointer to the fragment shader program source, compile shader program
const char *fragmentSourcePointer = [fragmentFileContents UTF8String];
glShaderSource(fragmentShaderID, 1, &fragmentSourcePointer, NULL);
glCompileShader(fragmentShaderID);
// check the fragment shader
glGetShaderiv(fragmentShaderID, GL_COMPILE_STATUS, &Result);
glGetShaderiv(fragmentShaderID, GL_INFO_LOG_LENGTH, &infoLogLength);
char fragmentShaderErrorMessage[infoLogLength];
glGetShaderInfoLog(fragmentShaderID, infoLogLength, NULL, fragmentShaderErrorMessage);
// print error message
NSLog(@"%@", [NSString stringWithUTF8String:fragmentShaderErrorMessage]);
// link the program
NSLog(@"Linking program...");
GLuint programID = glCreateProgram();
glAttachShader(programID, vertexShaderID);
glAttachShader(programID, fragmentShaderID);
glBindAttribLocation(programID, 0, "position");
glBindAttribLocation(programID, 1, "inColor");
glLinkProgram(programID);
// check the program
glGetProgramiv(programID, GL_LINK_STATUS, &Result);
glGetProgramiv(programID, GL_INFO_LOG_LENGTH, &infoLogLength);
char shaderProgramErrorMessage[max(infoLogLength, (int)1)];
glGetProgramInfoLog(programID, infoLogLength, NULL, shaderProgramErrorMessage);
// pring error message
NSLog(@"%@", [NSString stringWithUTF8String:shaderProgramErrorMessage]);
// delete shaders
glDeleteShader(vertexShaderID);
glDeleteShader(fragmentShaderID);
return programID;
}
最后的着色器:
#version 120
attribute vec4 position;
attribute vec4 inColor;
varying vec4 outColor;
void main()
{
gl_Position = position;
outColor = inColor;
}
而且
#version 120
varying vec4 outColor;
void main()
{
gl_FragColor = outColor;
}
答
看起来相当不错,虽然我看到一个错误。
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer[0]);
glEnableVertexAttribArray(0);
glVertexAttribPointer(VERTEX_POS_INDEX,
VERTEX_POS_SIZE,
GL_FLOAT,
GL_FALSE,
VERTEX_POS_SIZE*sizeof(vertices),
vertices);
如果您正在使用VBO,那么最终属性glVertexAttribPointer应该是从当前绑定的缓冲区开始的偏移量。
如果您使用的是顶点数组(无glBindBuffer),那么您将指向具有glVertexAttribPointer最终参数的顶点。
不过,既然你已经上传vertices
到缓冲和约束它,glVertexAttribPointer的终值应为偏移从顶点缓冲区,而你的情况,应该是0
的开始。
颜色缓冲区也是一样的错误。
我明白了。将张贴代码,但我被网站通知我需要10分才有这个特权。 – xBACP 2012-08-11 22:19:39
我不确定我是否理解。你想发布哪些代码?如果这篇文章解决了您的问题,则无需发布其他任何内容,但鼓励的操作是单击解决问题的答案旁边的绿色复选标记。否则,如果你仍然有麻烦,请让我知道。 @OneDaySoon – Tim 2012-08-11 22:25:46
我想以一个答案的形式发布更正后的代码,但因为我是10岁以下的新成员,所以我无法做到。 – xBACP 2012-08-11 22:28:52