我的要求与this question
相同我现在正处于我的opengl视图上设置UIImage的情况。 下面是我用来设置uiimage的完整代码。它还包括绘图代码。 使用下面的代码，我可以设置图像和绘图。
当我不在背景中设置图像时，它允许我绘制模糊和平滑绘图
但如果我设置了背景图片，则会绘制实体图纸
我希望在背景图片上顺利画画。
我使用了一些Apple的GLPaint代码进行绘图。
- (id)initWithCoder:(NSCoder*)coder
{
CGImageRef brushImage;
CGContextRef brushContext;
GLubyte *brushData;
size_t width, height;
if ((self = [super initWithCoder:coder]))
{
CAEAGLLayer *eaglLayer = (CAEAGLLayer *)self.layer;
eaglLayer.opaque = NO;
eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], kEAGLDrawablePropertyRetainedBacking,
kEAGLColorFormatRGBA8, kEAGLDrawablePropertyColorFormat,
nil];
_context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES1];
if (!_context || ![EAGLContext setCurrentContext:_context])
{
return nil;
}
{
brushImage = [UIImage imageNamed:@"Brush.png"].CGImage;
width = CGImageGetWidth(brushImage);
height = CGImageGetHeight(brushImage);
if(brushImage) {
brushData = (GLubyte *) calloc(width * height * 4, sizeof(GLubyte));
brushContext = CGBitmapContextCreate(brushData, width, width, 8, width * 4, CGImageGetColorSpace(brushImage), kCGImageAlphaPremultipliedLast);
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextDrawImage(brushContext, CGRectMake(0.0, 0.0, (CGFloat)width, (CGFloat)height), brushImage);
CGContextRelease(brushContext);
glGenTextures(1, &brushTexture);
glBindTexture(GL_TEXTURE_2D, brushTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, brushData);
free(brushData);
}
}
// Setup OpenGL states
glMatrixMode(GL_PROJECTION);
CGRect frame = self.bounds;
glOrthof(0, frame.size.width, 0, frame.size.height, -1, 1);
glViewport(0, 0, frame.size.width , frame.size.height);
glMatrixMode(GL_MODELVIEW);
glDisable(GL_DITHER);
glEnable(GL_TEXTURE_2D);
glEnableClientState(GL_VERTEX_ARRAY);
glEnable(GL_BLEND);
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_POINT_SPRITE_OES);
glTexEnvf(GL_POINT_SPRITE_OES, GL_COORD_REPLACE_OES, GL_TRUE);
glPointSize(10);
}
return self;
}
- (void)layoutSubviews
{
[EAGLContext setCurrentContext:_context];
[self destroyFramebuffer];
[self createFramebuffer];
if (texture) {
[self _updateContent];
glDeleteTextures(1, &texture);
texture = 0;
}
}
- (void)_updateContent {
NSUInteger width = self.frame.size.width;
NSUInteger height = self.frame.size.height;
CGFloat texWidth = (1.0 * width)/TEX_SIZE;
CGFloat texHeight = (1.0 * height)/TEX_SIZE;
GLfloat verts[12] = {
0, height,
width, height,
width, 0,
0, height,
0, 0,
width, 0
};
GLfloat txcoord[12] = {
0, texHeight,
texWidth, texHeight,
texWidth, 0,
0, texHeight,
0, 0,
texWidth, 0
};
[EAGLContext setCurrentContext:_context];
glBindFramebufferOES(GL_FRAMEBUFFER_OES, _viewFramebuffer);
glVertexPointer(2, GL_FLOAT, 0, verts);
glTexCoordPointer(2, GL_FLOAT, 0, txcoord);
glDrawArrays(GL_TRIANGLES, 0, 6);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glBindRenderbufferOES(GL_RENDERBUFFER_OES, _viewRenderbuffer);
[_context presentRenderbuffer:GL_RENDERBUFFER_OES];
glDisable(GL_TEXTURE_2D);
glDisable(GL_BLEND);
}
- (void)setContent:(UIImage*)image
{
if (image) {
// self.isNotEmpty = YES;
CGImageRef contentImage = image.CGImage;
[EAGLContext setCurrentContext:_context];
CGFloat w = CGImageGetWidth(contentImage);
CGFloat h = CGImageGetHeight(contentImage);
GLubyte *data = (GLubyte *)calloc(TEX_SIZE * TEX_SIZE * 4, sizeof(GLubyte));
CGContextRef ctx = CGBitmapContextCreate(data, TEX_SIZE, TEX_SIZE, 8, TEX_SIZE * 4, CGImageGetColorSpace(contentImage), kCGImageAlphaPremultipliedLast);
CGContextScaleCTM(ctx, 1, -1);
CGContextTranslateCTM(ctx, 0, -TEX_SIZE);
CGContextDrawImage(ctx, CGRectMake(0, 0, w, h), contentImage);
CGContextRelease(ctx);
if (!texture) {
glGenTextures(1, &texture);
}
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, TEX_SIZE, TEX_SIZE, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
free(data);
}
[self setNeedsLayout];
glDisable(GL_VERTEX_ARRAY);
}
//在touchMoved
上调用- (void) renderLineFromPoint:(CGPoint)start toPoint:(CGPoint)end
{
glEnable(GL_BLEND);
if(1){
sharedDelegate = [AppDelegate appDelegate];
static GLfloat* vertexBuffer = NULL;
static NSUInteger vertexMax = 64;
NSUInteger vertexCount = 0,
count,
i;
GLenum err;
glColor4f(1.0, 0.0, 1.0, 1.0);
// Convert locations from Points to Pixels
CGFloat scale = self.contentScaleFactor;
start.x *= scale;
start.y *= scale;
end.x *= scale;
end.y *= scale;
// Allocate vertex array buffer
if(vertexBuffer == NULL)
vertexBuffer = malloc(vertexMax * 2 * sizeof(GLfloat));
// Add points to the buffer so there are drawing points every X pixels
count = MAX(ceilf(sqrtf((end.x - start.x) * (end.x - start.x) + (end.y - start.y) * (end.y - start.y)) / kBrushPixelStep), 1);
for(i = 0; i < count; ++i) {
if(vertexCount == vertexMax) {
vertexMax = 2 * vertexMax;
vertexBuffer = realloc(vertexBuffer, vertexMax * 2 * sizeof(GLfloat));
}
vertexBuffer[2 * vertexCount + 0] = start.x + (end.x - start.x) * ((GLfloat)i / (GLfloat)count);
vertexBuffer[2 * vertexCount + 1] = start.y + (end.y - start.y) * ((GLfloat)i / (GLfloat)count);
vertexCount += 1;
}
if(sharedDelegate.boolIsEraser)
{
glColor4f(1.0, 1.0, 1.0, 0.5);
glBlendFunc( GL_ZERO, GL_ONE_MINUS_SRC_ALPHA);
}
// Render the vertex array
glVertexPointer(2, GL_FLOAT, 0, vertexBuffer);
glDrawArrays(GL_POINTS, 0, vertexCount);
if(sharedDelegate.boolIsEraser){
// at last restore the mixed-mode
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
}
glBindRenderbufferOES(GL_RENDERBUFFER_OES, _viewRenderbuffer);
[_context presentRenderbuffer:GL_RENDERBUFFER_OES];
err = glGetError();
if (err != GL_NO_ERROR)
NSLog(@"Error in frame. glError: 0x%04X", err);
}
}
完成此任务的任何解决方法？ 我差不多到了我的目标，但却被困在这里。任何帮助都将受到赞赏。
答案 0 :(得分：1)
您可以尝试将阴影颜色设置为与笔触颜色相同，然后将笔划模糊半径设置为从您希望模糊扩展的笔划边缘开出的多个点。您可能希望将阴影偏移设置为CGSizeZero。
答案 1 :(得分：1)
您可以尝试This Link
中的openGL代码或试试这个
CGSize offset;
float blur;//set this variable as per your requirement
offset.width = 10;
offset.height = -10;
CGContextSetShadow(context, offset, blur);
答案 2 :(得分：1)
我得到了解决方案......
剩下的就是我在opengl视图中绘制UIImage后需要设置我的opengl状态。我在初始化画笔纹理时也做了同样的事情......
我刚刚在LayoutSubviews方法
_updateContent方法中添加了以下代码
// Setup OpenGL states
glMatrixMode(GL_PROJECTION);
CGRect frame = self.bounds;
glOrthof(0, frame.size.width, 0, frame.size.height, -1, 1);
glViewport(0, 0, frame.size.width , frame.size.height);
glMatrixMode(GL_MODELVIEW);
glDisable(GL_DITHER);
glEnable(GL_TEXTURE_2D);
glEnableClientState(GL_VERTEX_ARRAY);
glEnable(GL_BLEND);
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_POINT_SPRITE_OES);
glTexEnvf(GL_POINT_SPRITE_OES, GL_COORD_REPLACE_OES, GL_TRUE)
现在这段代码工作正常......
答案 3 :(得分：0)
你可以使用 CGContextSetBlendMode（context，kCGBlendModeClear）ike真正的橡皮擦效果