将openGL ES纹理读取到原始数组
将openGL ES纹理读取到原始数组
提问于 2012-06-09 03:07:14
我正在尝试从openGL ES中的RGBA纹理中获取字节。我想我是在模仿香草openGL中的glGetTexImage。就像现在一样，从调用glClear开始，像素都是空的，而不是我正在寻找的纹理数据。
这是一个从Sparrow Framework扩展SPTexture的类别中的方法。
-(NSMutableData *) getPixelsFromTexture
{
GLsizei width = (GLsizei) self.width;
GLsizei height = (GLsizei) self.height;
GLint oldBind = 0;
glGetIntegerv(GL_TEXTURE_BINDING_2D, &oldBind);
glBindTexture(GL_TEXTURE_2D, self.textureID);
GLuint fbo[1];
glGenFramebuffersOES(1, fbo);
glBindFramebufferOES(GL_FRAMEBUFFER_OES, fbo[0]);
GLuint rbo[1];
glGenRenderbuffersOES(1, rbo);
glBindRenderbufferOES(GL_RENDERBUFFER_OES, rbo[0]);
glRenderbufferStorageOES(GL_RENDERBUFFER_OES, GL_RGBA4_OES, width, height);
glFramebufferRenderbufferOES(GL_FRAMEBUFFER_OES, GL_COLOR_ATTACHMENT0_OES, GL_RENDERBUFFER_OES, rbo[0]);
GLenum status = glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES);
if (status != GL_FRAMEBUFFER_COMPLETE_OES) {
NSLog(@"Incomplete FBO");
}
// draw
static float texCoords[8] = { 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f };
static float vertexCoords[8] = { -1.0f, -1.0f, 1-.0f, 1.0f, 1.0f, 1.0f, 1.0f, -1.0f };
glMatrixMode (GL_PROJECTION);
glPushMatrix();
glLoadIdentity ();
glOrthof(0.0f, self.width, self.height, 0.0f, 0.0f, 1.0f);
glMatrixMode (GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glClear(GL_COLOR_BUFFER_BIT);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glEnableClientState(GL_VERTEX_ARRAY);
glTexCoordPointer(2, GL_FLOAT, 0, texCoords);
glVertexPointer(2, GL_FLOAT, 0, vertexCoords);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
glPopMatrix();
glMatrixMode(GL_PROJECTION);
glPopMatrix();
// end draw
GLsizei count = width * height * 4;
GLubyte * pixels = (GLubyte *)malloc((sizeof(GLubyte) * count));
glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
glBindRenderbufferOES(GL_RENDERBUFFER_OES, 0);
glBindFramebufferOES(GL_FRAMEBUFFER_OES, 0);
glBindTexture(GL_TEXTURE_2D, oldBind);
glDeleteRenderbuffersOES(1, rbo);
glDeleteFramebuffersOES(1, fbo);
return [NSMutableData dataWithBytes:pixels length:count];
}我做错了什么？
Stack Overflow用户
回答已采纳
发布于 2012-06-11 23:21:06
所以，我最终能够使用here代码的一个变体来解决这个问题。我的代码是：
@interface SPRenderTexture (RenderToImage)
- (NSMutableData *)renderToPixelData;
@end
@implementation SPRenderTexture (RenderToImage)
- (NSMutableData *)renderToPixelData
{
__block NSMutableData * pixels = nil;
[self bundleDrawCalls:^()
{
float scale = [SPStage contentScaleFactor];
int width = scale * self.width;
int height = scale * self.height;
int nrOfColorComponents = 4; //RGBA
int rawImageDataLength = width * height * nrOfColorComponents;
GLenum pixelDataFormat = GL_RGBA;
GLenum pixelDataType = GL_UNSIGNED_BYTE;
GLubyte *rawImageDataBuffer = (GLubyte *) malloc(rawImageDataLength);
glReadPixels(0, 0, width, height, pixelDataFormat, pixelDataType, rawImageDataBuffer);
pixels = [[NSMutableData alloc] initWithBytes:rawImageDataBuffer length:rawImageDataLength];
}];
return [pixels autorelease];
}
@end我希望这对其他人有用。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/10954703
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