Ios OpenGL ES旋转2D纹理
我对OpenGL非常陌生。我正在iPad上构建一个绘画应用程序,我有点像苹果的例子。基本上,我想画一个纹理的触摸位置,每次触摸被移动。我能够从图像加载纹理,并使用以下代码将其绘制到视图: 初始总账:Ios OpenGL ES旋转2D纹理,ios,objective-c,rotation,opengl-es-2.0,texture2d,Ios,Objective C,Rotation,Opengl Es 2.0,Texture2d,我对OpenGL非常陌生。我正在iPad上构建一个绘画应用程序,我有点像苹果的例子。基本上,我想画一个纹理的触摸位置,每次触摸被移动。我能够从图像加载纹理,并使用以下代码将其绘制到视图: 初始总账: - (BOOL)initGL { glGenFramebuffers(1, &viewFramebuffer); glGenRenderbuffers(1, &viewRenderbuffer); glBindFramebuffer(GL_FRAMEBUFFER, viewFram
- (BOOL)initGL {
glGenFramebuffers(1, &viewFramebuffer);
glGenRenderbuffers(1, &viewRenderbuffer);
glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
[context renderbufferStorage:GL_RENDERBUFFER fromDrawable:(id<EAGLDrawable>)self.layer];
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, viewRenderbuffer);
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &backingWidth);
glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &backingHeight);
if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
{
NSLog(@"failed to make complete framebuffer object %x", glCheckFramebufferStatus(GL_FRAMEBUFFER));
return NO;
}
glViewport(0, 0, backingWidth, backingHeight);
glGenBuffers(1, &vboId);
brushTexture = [self textureFromName:@"Brush2.png"];
[self setupShaders];
glEnable(GL_BLEND);
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
return YES;
}
着色器:
- (void)setupShaders {
for (int i = 0; i < NUM_PROGRAMS; i++)
{
char *vsrc = readFile(pathForResource(program[i].vert));
char *fsrc = readFile(pathForResource(program[i].frag));
GLsizei attribCt = 0;
GLchar *attribUsed[NUM_ATTRIBS];
GLint attrib[NUM_ATTRIBS];
GLchar *attribName[NUM_ATTRIBS] = {
"inVertex",
};
const GLchar *uniformName[NUM_UNIFORMS] = {
"MVP", "pointSize", "vertexColor", "texture",
};
for (int j = 0; j < NUM_ATTRIBS; j++)
{
if (strstr(vsrc, attribName[j]))
{
attrib[attribCt] = j;
attribUsed[attribCt++] = attribName[j];
}
}
glueCreateProgram(vsrc, fsrc,
attribCt, (const GLchar **)&attribUsed[0], attrib,
NUM_UNIFORMS, &uniformName[0], program[i].uniform,
&program[i].id);
free(vsrc);
free(fsrc);
if (i == PROGRAM_POINT)
{
glUseProgram(program[PROGRAM_POINT].id);
glUniform1i(program[PROGRAM_POINT].uniform[UNIFORM_TEXTURE], 0);
GLKMatrix4 projectionMatrix = GLKMatrix4MakeOrtho(0, backingWidth, 0, backingHeight, -1, 1);
GLKMatrix4 modelViewMatrix = GLKMatrix4Identity; // this sample uses a constant identity modelView matrix
GLKMatrix4 MVPMatrix = GLKMatrix4Multiply(projectionMatrix, modelViewMatrix);
glUniformMatrix4fv(program[PROGRAM_POINT].uniform[UNIFORM_MVP], 1, GL_FALSE, MVPMatrix.m);
glUniform1f(program[PROGRAM_POINT].uniform[UNIFORM_POINT_SIZE], brushTexture.width / kBrushScale);
glUniform4fv(program[PROGRAM_POINT].uniform[UNIFORM_VERTEX_COLOR], 1, brushColor);
}
}
glError();
-(无效)设置着色器{
对于(int i=0;i
}
抽签:
-(void)renderLineFromPoint:(CGPoint)start toPoint:(CGPoint)end{
静态GLfloat*vertexBuffer=NULL;
静态整数vertexMax=64;
NSU整数vertexCount=0,
计数
我
[EagleContext setCurrentContext:context];
glBindFramebuffer(GL_FRAMEBUFFER,viewFramebuffer);
CGFloat scale=self.contentScaleFactor;
start.x*=刻度;
start.y*=刻度;
end.x*=刻度;
结束。y*=刻度;
if(vertexBuffer==NULL)
vertexBuffer=malloc(vertexMax*2*sizeof(GLfloat));
计数=最大值(ceilf(sqrtf((end.x-start.x)*(end.x-start.x)+(end.y-start.y)*(end.y-start.y))/kBrushPixelStep),1);
对于(i=0;i
}
我缺少的是在每次绘制纹理之前旋转纹理的方法。我尝试使用旋转的CGContext初始化纹理,但每次绘制点时都需要太多的处理来调用。有人能告诉我一个更好的方法来旋转纹理吗。我对OpenGL非常陌生,如有任何帮助,我将不胜感激。您可以使用
GL\u纹理
矩阵模式对纹理坐标应用变换。例如,要围绕z轴逆时针旋转纹理坐标90度,请执行以下操作:
glMatrixMode(GL_TEXTURE);
glTranslatef(1.0f, 0.0f, 0.0f);
glRotatef(90.0f, 0.0f, 0.0f, 1.0f);
glMatrixMode(GL_MODELVIEW);
请注意平移,以在围绕原点旋转后将纹理坐标范围保持在[0.0,1.0]范围内。我先前对类似问题的回答更详细地解释了其中的一些问题:
我通常会尽量避免推荐与海报要求不同的技术,但在这种情况下我无能为力:如果您是OpenGL ES新手,我强烈建议您跳过ES 1.x。我相信现在大多数人会认为这是过时的API。例如,如果您导航到www.khronos.com()上的手册页,您将注意到不再有指向ES 1.x的链接。当然,如果您浏览更多内容,内容仍然存在,但这清楚地表明,ES 2.0目前被视为基准。非常感谢您发布了答案。然而,我对上面的代码有点困惑。我试着把它放在glDrawArrays函数的前面,但是没有结果。纹理仍然以原始方向绘制。代码应该放在其他地方吗?嗯,看起来你没有在任何地方显式设置纹理坐标。必须是为您生成它们的
GL\u POINT\u SPRITE\u OES
东西。可能纹理变换未应用于生成的纹理坐标。根据文档,点精灵始终在窗口坐标中轴对齐。海报将需要切换到使用实际的几何体,而不是用于粒子的扩展。@Tommy我该怎么做?你能给我指一下正确的方向吗?对不起,我的noobinessDraw四边形的位置和纹理坐标,而不是点。或使用ES 2.0.:)
- (void)renderLineFromPoint:(CGPoint)start toPoint:(CGPoint)end {
static GLfloat* vertexBuffer = NULL;
static NSUInteger vertexMax = 64;
NSUInteger vertexCount = 0,
count,
i;
[EAGLContext setCurrentContext:context];
glBindFramebuffer(GL_FRAMEBUFFER, viewFramebuffer);
CGFloat scale = self.contentScaleFactor;
start.x *= scale;
start.y *= scale;
end.x *= scale;
end.y *= scale;
if(vertexBuffer == NULL)
vertexBuffer = malloc(vertexMax * 2 * sizeof(GLfloat));
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;
}
glBindBuffer(GL_ARRAY_BUFFER, vboId);
glBufferData(GL_ARRAY_BUFFER, vertexCount*2*sizeof(GLfloat), vertexBuffer, GL_DYNAMIC_DRAW);
glEnableVertexAttribArray(ATTRIB_VERTEX);
glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, GL_FALSE, 0, 0);
glUseProgram(program[PROGRAM_POINT].id);
glDrawArrays(GL_POINTS, 0, (int)vertexCount);
glBindRenderbuffer(GL_RENDERBUFFER, viewRenderbuffer);
[context presentRenderbuffer:GL_RENDERBUFFER];
glMatrixMode(GL_TEXTURE);
glTranslatef(1.0f, 0.0f, 0.0f);
glRotatef(90.0f, 0.0f, 0.0f, 1.0f);
glMatrixMode(GL_MODELVIEW);