opengl-es

问题 I'm writing a game for IPhone in Opengl ES, and I'm experiencing a problem with alpha blending: I'm using glBlendFunc(Gl.GL_SRC_ALPHA, Gl.GL_ONE_MINUS_SRC_ALPHA) to achieve alpha blending and trying to compose a scene with several "layers" so I can move them separately instead of having a static image. I created a preview in photoshop and then tried to achieve the same result in the iphone, but a black halo is shown when I blend a texture with semi-transparent regions. I attached an image. In

问题 If I have custom renderer in opengl-es prepared: public void onDrawFrame(GL10 gl) { gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); // here i want to draw line from [0, 0, 0] to [1, 0, 0] } What is the easiest and shortest way to draw line? In ordinary OpenGL it is: glBegin(GL_LINES); glVertex3f(0, 0, 0); glVertex3f(1, 0, 0); glEnd(); But how can i get the same effect with OpenGL ES? 回答1: I am new to new to OpenGL ES 2.0 but I created a line class. public class Line { private

问题 If I have custom renderer in opengl-es prepared: public void onDrawFrame(GL10 gl) { gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); // here i want to draw line from [0, 0, 0] to [1, 0, 0] } What is the easiest and shortest way to draw line? In ordinary OpenGL it is: glBegin(GL_LINES); glVertex3f(0, 0, 0); glVertex3f(1, 0, 0); glEnd(); But how can i get the same effect with OpenGL ES? 回答1: I am new to new to OpenGL ES 2.0 but I created a line class. public class Line { private

问题 If I have custom renderer in opengl-es prepared: public void onDrawFrame(GL10 gl) { gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); // here i want to draw line from [0, 0, 0] to [1, 0, 0] } What is the easiest and shortest way to draw line? In ordinary OpenGL it is: glBegin(GL_LINES); glVertex3f(0, 0, 0); glVertex3f(1, 0, 0); glEnd(); But how can i get the same effect with OpenGL ES? 回答1: I am new to new to OpenGL ES 2.0 but I created a line class. public class Line { private

问题 I would like to have a gradient background in OpenGL I found these two links, but I cannot reproduce it: OpenGL gradient fill on iPhone looks striped OpenGL gradient banding on Android I tried the following of the first link: // Begin Render //IntBuffer redBits = null, greenBits = null, blueBits = null; //gl.glGetIntegerv (GL10.GL_RED_BITS, redBits); // ==> 8 //gl.glGetIntegerv (GL10.GL_GREEN_BITS, greenBits); // ==> 8 //gl.glGetIntegerv (GL10.GL_BLUE_BITS, blueBits); // ==> 8 gl.glDisable

问题 I would like to have a gradient background in OpenGL I found these two links, but I cannot reproduce it: OpenGL gradient fill on iPhone looks striped OpenGL gradient banding on Android I tried the following of the first link: // Begin Render //IntBuffer redBits = null, greenBits = null, blueBits = null; //gl.glGetIntegerv (GL10.GL_RED_BITS, redBits); // ==> 8 //gl.glGetIntegerv (GL10.GL_GREEN_BITS, greenBits); // ==> 8 //gl.glGetIntegerv (GL10.GL_BLUE_BITS, blueBits); // ==> 8 gl.glDisable

问题 I'm writing an app on iOS allows drawing free style (using finger) and drawing image on screen. I use OpenGL ES to implement. I have 2 functions, one is drawing free style, one is drawing texture --- Code drawing free style - (void)drawFreeStyle:(NSMutableArray *)pointArray { //Prepare vertex data ..... // Load data to the Vertex Buffer Object glBindBuffer(GL_ARRAY_BUFFER, vboId); glBufferData(GL_ARRAY_BUFFER, vertexCount*2*sizeof(GLfloat), vertexBuffer, GL_DYNAMIC_DRAW);

问题 I'm writing a program that is supposed to draw 3D parametric shapes in webgl. The code I have currently seems to work (mostly) for a sphere, but when I switch out the equations used to find x, y, and z, for a torus, only the top half of the torus is being rendered (in the x-y plane). All of the parametric equations I have (for a sphere, a torus, and a cylinder) work when just the 2d canvas context is used without any webgl; however, when webgl is used, there seems to be a problem. In addition

问题 I'm saving the depth value via fragmend shader in the color buffer of the main framebuffer (in 'opengl es' there is no way to read the depth buffer via glReadPixels()). Additionally I need the maximum precision of 32-bit, that's why I use the rgba of the colorbuffer. But I realized that using also the alpha channel the results are not always correct, maybe because of some post fragmend operations. The following works: set fragColor.a = 1 (but then I'm loosing one channel) or set gl_FragDepth

问题 I'm making the following call on iOS using OpenGL ES 3: glTexImage2D(GL_TEXTURE_2D, // target 0, // level GL_RGBA, // internalformat 1024, // width 692, // height 0, // border GL_RGBA, // format GL_UNSIGNED_BYTE, // type NULL); // data However, it is returning GL_INVALID_OPERATION . There are a slew of reasons that GL_INVALID_OPERATION might be returned. However, I can't spot any that are relevant to my situation. The weird thing is if I just ignore the error, things seem to work anyway.