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  • Setting ModelView matrix using rotate, translate, etc.. vs setting manual matrix

    - by guymic
    When setting the ModelView matrix you normally go through several transformations from the identity matrix. for example: glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glRotatef(270.0f, 0.0f, 0.0f, 1.0f); glTranslatef(-rect.size.height / 2, -rect.size.width / 2, 0.0f); Instead of doing those operations one after the other (assume there are more than two), wouldn't it be more efficient to simply pre-calculate the resulting matrix and set the ModelView matrix to this manual matrix?

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  • Getting the MODELVIEW matrix...

    - by james.ingham
    Hi, I've been pulling my hair out trying to get some matrix calculations working properly and started to wonder. If I have the following: glPushMatrix(); float m[16]; glGetFloatv(GL_MODELVIEW_MATRIX, m); glPopMatrix(); What should I expect the values of m to equal? Currently I'm getting these values and I'm confused as to where they're coming from: -1, 0, 0, 0, 0, -0.6139, 0.7893522, 0, 0, 0.789352238, 0.61394, 0, 0, 0.0955992, -1.344529, 1, I'm assuming there is something which affects this, but I'm not sure what. Could anyone help? I've tried changing pretty much anything but everytime I push the matrix stack I always get this matrix straight away! I don't think this makes a difference but I'm using OpenGLES. Thanks

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  • 3D Texture mapping

    - by Joe Cannatti
    In an .obj, file it is possible to specify 3 values for a vt line. vt 0.769645 0.729072 0.00000000 The .obj spec says its for "depth". What does this actually do and when is it useful?

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  • EAGLView orientation changes and strange buffering

    - by Drew
    I'm writing an app that offloads some heavy drawing into an EAGLView, and it does some lightweight stuff in UIKit on top. It seems that the GL render during an orientation change is cached somewhere, and I can't figure out how to get access to it. Specifically: After an orientation change, calling glClear(GL_COLOR_BUFFER_BIT) isn't enough to clear the GL display (drawing is cached somewhere?) How can I clear this cache? After an orientation change, glReadPixel() can no longer access pixels drawn before the orientation change. How can I get access to where this is stored?

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  • Corrupted image if variable is not static

    - by Jaka Jancar
    I'm doing the following: static GLfloat vertices[3][3] = { {0.0, 1.0, 0.0}, {1.0, 0.0, 0.0}, {-1.0, 0.0, 0.0} }; glColor4ub(255, 0, 0, 255); glEnableClientState(GL_VERTEX_ARRAY); glVertexPointer(3, GL_FLOAT, 0, vertices); glDrawArrays(GL_TRIANGLES, 0, 9); glDisableClientState(GL_VERTEX_ARRAY); This works ok: However, if I remove static from vertices and therefore re-create the data on the stack on each rendering, I get the following: This happens both on the simulator and on the device. Should I be keeping the variables around after I call glDrawArrays?

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  • OpenGLES - Rendering a background image only once and not wiping it

    - by chaosbeaker
    Hello, first time asking a question here but been watching others answers for a while. My own question is one for improving the performance of my program. Currently I'm wiping the viewFrameBuffer on each pass through my program and then rendering the background image first followed by the rest of my scene. I was wondering how I go about rendering the background image once, and only wiping the rest of the scene for updating/re-rendering. I tried using a seperate buffer but I'm not sure how to present this new buffer to the render buffer. // Set the current EAGLContext and bind to the framebuffer. This will direct all OGL commands to the // framebuffer and the associated renderbuffer attachment which is where our scene will be rendered [EAGLContext setCurrentContext:context]; glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer); // Define the viewport. Changing the settings for the viewport can allow you to scale the viewport // as well as the dimensions etc and so I'm setting it for each frame in case we want to change i glViewport(0, 0, screenBounds.size.width , screenBounds.size.height); // Clear the screen. If we are going to draw a background image then this clear is not necessary // as drawing the background image will destroy the previous image glClearColor(0.0f, 1.0f, 0.0f, 1.0f); glClear(GL_COLOR_BUFFER_BIT); // Setup how the images are to be blended when rendered. This could be changed at different points during your // render process if you wanted to apply different effects glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); switch (currentViewInt) { case 1: { [background render:CGPointMake(240, 0) fromTopLeftBottomRightCenter:@"Bottom"]; // Other Rendering Code }} // Bind to the renderbuffer and then present this image to the current context glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer); [context presentRenderbuffer:GL_RENDERBUFFER_OES]; Hopefully by solving this I'll also be able to implement another buffer just for rendering particles as I can set them to always use a black background as their alpha source. Any help is greatly appreciated

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  • What does setting the GL color before doing a texture mapping operation do?

    - by quixoto
    I am looking at some sample code in a book that creates a jittered antialiasing effect by repeatedly rendering a scene (at different offsets) onto a offscreen texture, then using that texture to repeatedly draw a quad in the main view with some blend stuff set up. To accumulate the color "correctly", the code is setting the color like so: glColor4f(f, f, f, 1); where f is 1.0/number_of_samples, and then binding the offscreen texture and rendering it. Since textures come with their own color and alpha data, what is the effect (mathematically and intuitively) that setting the overall "color" in advance achieves? Thanks.

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  • Set brightness, contrass on selected image

    - by Viral
    hi, I want to set brightness and contrast on the image that is selected from the photo library of iphone, is there any way to do the same using/not using open GLES. I've got some code from the developer.apple.com but that is for a single image and i can't use images from photo library, do any one know please let me know how to this. regards viral.

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  • How to set image on EAGL VIEW

    - by Viral
    hi, I want to put images from my photo library in to the EAGL view for some further processing. The image that are already in our resources folder will be taken by itself but mltiple or images from photo library can't. So any one knows how to put image on EAGL view in open GLES. Regtards viral

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  • Texture repeats even with GL_CLAMP_TO_EDGE set

    - by Lliane
    Hi, i'm trying to put a translucing texture on a face which uses points 1 to 4 (don't mind the numbers) on the following screenshot Sadly as you can see the texture repeats herself in both dimensions, I tried to switch the TEXTURE_WRAP_S from REPEAT to CLAMP_to_EDGE but it doesn't change anything. Texture loading code is here : gl.glBindTexture(gl.GL_TEXTURE_2D, mTexture.get(4)); gl.glActiveTexture(4); gl.glTexParameterf(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MIN_FILTER, gl.GL_LINEAR); gl.glTexParameterf(gl.GL_TEXTURE_2D, gl.GL_TEXTURE_MAG_FILTER, gl.GL_LINEAR); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_CLAMP_TO_EDGE); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_CLAMP_TO_EDGE); gl.glTexImage2D(gl.GL_TEXTURE_2D, 0, gl.GL_RGBA, shadowbmp.width, shadowbmp.height, 0, gl.GL_RGBA, gl.GL_UNSIGNED_SHORT_4_4_4_4, shadowbmp.buffer); Texture coordinates are the following : float shadow_bot_text[] = { 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f }; Thanks

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  • How to get X,Y,Z rotations of vertices on a sphere at the origin?

    - by Stoff81
    Hey, I have a sphere in my game world and i would like to place a plane at each vertex on this sphere for debugging purposes. The planes should be orientated so that they lie flat against the sphere (perpendicular to the normals). The sphere is located at the origin, so all the vertices are relative to that. If my thinking is correct, i should be able to do this using the positions of the vertices and some simple trigonometry. I have tried a few combinations but have had no joy yet. I would greatly appreciate some help on this. Thanks. Here is my code: float xRot = RADIANS_TO_DEGREES(sinf(vertex.x/PLANET_RADIUS)); float yRot = RADIANS_TO_DEGREES(cosf(vertex.y/PLANET_RADIUS)); glRotatef(xRot, 1.0, 0, 0); glRotatef(yRot, 0, 1.0, 0);

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  • Why don't I need to bind my vertex buffer object before calling glDrawArrays?

    - by valmo
    I'm a bit confused why this still renders. I thought you need to bind a vertex buffer object so that glDrawArrays knows which vertex buffer to use. Here is my initialisation code.. // Create and bind vertex array to store vertex attribute states. glGenVertexArraysOES(NUM_VERTEX_ARRAYS, &m_vertexArray); glBindVertexArrayOES(m_vertexArray); // Create and bind vertex buffer to store vertex data. glGenBuffers(NUM_VERTEX_BUFFERS, &m_vertexBuffer); glBindBuffer(GL_ARRAY_BUFFER, m_vertexBuffer); glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex) * 36, &m_vertices[0], GL_STATIC_DRAW); glEnableVertexAttribArray(VertexAttribPosition); glVertexAttribPointer(VertexAttribPosition, 3, GL_FLOAT, GL_FALSE, 24, BUFFER_OFFSET(0)); glEnableVertexAttribArray(VertexAttribNormal); glVertexAttribPointer(VertexAttribNormal, 3, GL_FLOAT, GL_FALSE, 24, BUFFER_OFFSET(12)); glBindBuffer(GL_ARRAY_BUFFER, 0); glBindVertexArrayOES(0); Here is my render code. I'm confused why glDrawArrays still works when I bind 0 to GL_ARRAY_BUFFER. glBindVertexArrayOES(m_vertexArray); glBindBuffer(GL_ARRAY_BUFFER, 0); glDrawArrays(GL_TRIANGLES, 0, 36); glBindVertexArrayOES(0);

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  • The most efficient method of drawing multiple quads in OpenGL

    - by CPatton
    I'm not very keen with OpenGL and I was wondering if someone could give me some insight on this. I'm a 'seasoned' programmer, I've read the redbook about VBOs and the like, but I was wondering from a more experienced person about the best/most efficient way of achieving this. I've been producing this 2d tile-based game engine to be used in several projects. I have a class called "ScreenObject" which is mainly composed of a Dictionary<Point, Tile> The Point key is to show where to render the Tile on the screen, and the Tile contains one or more textures to be drawn at that point. This ScreenObject is where the tiles will be modified, deleted, added, etc.. My original method of drawing the tiles in the testing I've done was to iterate through the ScreenObject and draw each quad at each location separately. From what I've read, this is a massive waste of resources. It wasn't horribly slow in the testing, but after I've completed the animation classes and effect classes, I'm sure it would be extremely slow. And one last thing, if you wouldn't mind.. As I said before, the Tile class can contain multiple textures to be drawn at the Point location on the screen. I recognize possibly two options for me here. Either add a quad at that location for each texture to be drawn, or, somehow.. use a multiple texture for the same quad (if it's possible). Even if each tile contained one texture only, that would be 64 quads to be drawn on the screen. Most of the tiles will contain 2-5 textures, so the number of total quads would increase dramatically with this method. Would it be feasible to add a quad for each new texture, or am I ignoring a better way to do this? Just need some help understanding this if you don't mind :) I've tried to be as concise as possible, and I'd greatly appreciate any responses.. and even some criticism. Programming is often a learning process and one who develops seems to never stops learning. Thanks for your time.

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  • OpenGL 2D Texture Mapping problem.

    - by gutsblow
    Hi there, I am relatively new to OpenGL and I am having some issues when I am rendering an image as a texture for a QUAD which is as the same size of the image. Here is my code. I would be very grateful if someone helps me to solve this problem. The image appears way smaller and is squished. (BTW, the image dimensions are 500x375). glGenTextures( 1, &S_GLator_InputFrameTextureIDSu ); glBindTexture(GL_TEXTURE_2D, S_GLator_InputFrameTextureIDSu); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); glTexImage2D( GL_TEXTURE_2D, 0, 4, S_GLator_EffectCommonData.mRenderBufferWidthSu, S_GLator_EffectCommonData.mRenderBufferHeightSu, 0, GL_RGBA, GL_UNSIGNED_BYTE, dataP); glBindTexture(GL_TEXTURE_2D, S_GLator_InputFrameTextureIDSu); glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, S_GLator_EffectCommonData.mRenderBufferWidthSu, S_GLator_EffectCommonData.mRenderBufferHeightSu, GL_RGBA, GL_UNSIGNED_BYTE, bufferP); //set the matrix modes glMatrixMode( GL_PROJECTION ); glLoadIdentity(); //gluPerspective( 45.0, (GLdouble)widthL / heightL, 0.1, 100.0 ); glOrtho (0, 1, 0, 1, -1, 1); // Set up the frame-buffer object just like a window. glViewport( 0, 0, widthL, heightL ); glDisable(GL_DEPTH_TEST); glClearColor( 0.0f, 0.0f, 0.0f, 0.0f ); glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); glMatrixMode( GL_MODELVIEW ); glLoadIdentity(); glBindTexture( GL_TEXTURE_2D, S_GLator_InputFrameTextureIDSu ); //Render the geometry to the frame-buffer object glBegin(GL_QUADS); //input frame glColor4f(1.f,1.f,1.f,1.f); glTexCoord2f(0.0f,0.0f); glVertex3f(0.f ,0.f ,0.0f); glTexCoord2f(1.0f,0.0f); glVertex3f(1.f ,0.f,0.0f); glTexCoord2f(1.0f,1.f); glVertex3f(1.f ,1.f,0.0f); glTexCoord2f(0.0f,1.f); glVertex3f(0.f ,1.f,0.0f); glEnd();

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  • OpenGL Polygon Stipple Not Working On Different Machine

    - by FranticPedantic
    I have a situation where I am trying to draw a semi-transparent rectangle over a background that is not using openGL and so I can not use blending. I decided to use polygon stippling for a 'screen door transparency' effect as recommended by some. It works fine on my machine and some others, but on some machines with slightly old Intel graphics cards it's failing to render the rectangle at all. If I turn off polygon stipple, it renders fine (but without the stipple). I have compared many of the state variables that I thought might affect it (see code) between machines and they are all the same, and I get no errors. static const GLubyte stipplePatternChkr[128]; //definition omitted for clarity //but works on my machine // stipple the box glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); glColor4ubv(Color(COLORREF_PADGRAY)); glEnable(GL_POLYGON_STIPPLE); glPolygonStipple(stipplePatternChkr); CRect rcStipple(dim); rcStipple.DeflateRect(padding - 1, padding - 1); glBegin(GL_QUADS); glVertex2i(rcStipple.left, rcStipple.bottom); glVertex2i(rcStipple.right, rcStipple.bottom); glVertex2i(rcStipple.right, rcStipple.top); glVertex2i(rcStipple.left, rcStipple.top); glEnd(); glDisable(GL_POLYGON_STIPPLE); int err = glGetError(); if (err != GL_NO_ERROR) { TRACE("glError(%s: %s)\n", s, gluErrorString(err)); } float x; glGetFloatv(GL_UNPACK_ALIGNMENT, &x); TRACE("unpack alignment %f\n", x); glGetFloatv(GL_UNPACK_IMAGE_HEIGHT, &x); TRACE("unpack height %f\n", x); glGetFloatv(GL_UNPACK_LSB_FIRST, &x); TRACE("unpack lsb %f\n", x); glGetFloatv(GL_UNPACK_ROW_LENGTH, &x); TRACE("unpack length %f\n", x); glGetFloatv(GL_UNPACK_SKIP_PIXELS, &x); TRACE("upnack skip %f\n", x); glGetFloatv(GL_UNPACK_SWAP_BYTES, &x); TRACE("upnack swap %f\n", x);

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  • OpenGL, problems with GL_MODELVIEW GL_PROJECTION...

    - by Marcos Roriz
    Guys, I'm trying to finish up my homework but I'm having some problems here on these models on openGL... any Idea why is my draw not happening? One thing that strange is that if I change to gluPerspective it works.. #include <GL/glut.h> #include <stdlib.h> #include <stdio.h> static int shoulder = 0; static int elbow = 0; void init(void) { glClearColor(1.0, 1.0, 1.0, 0.0); } void display(void) { glClear(GL_COLOR_BUFFER_BIT); glPushMatrix(); /* BASE */ glRotatef((GLfloat) shoulder, 0.0, 0.0, 1.0); glTranslatef(1.0, 0.0, 0.0); glPushMatrix(); //glScalef(2.0, 0.4, 1.0); glBegin(GL_QUADS); glColor3f(0, 0, 0); glVertex2f(0.0, 0.0); glVertex2f(0.0, 10.0); glVertex2f(10.0, 10.0); glVertex2f(10.0, 0.0); glEnd(); glPopMatrix(); glPopMatrix(); glutSwapBuffers(); } void reshape(int w, int h) { glViewport(0, 0, (GLsizei) w, (GLsizei) h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho((GLfloat)-w/2, (GLfloat)w/2, (GLfloat)-h/2, (GLfloat)h/2, -1.0, 1.0); // modo de projecao ortogonal glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslatef(0.0, 0.0, -5.0); } void keyboard(unsigned char key, int x, int y) { switch (key) { case 's': shoulder = (shoulder + 5) % 360; glutPostRedisplay(); break; case 'S': shoulder = (shoulder - 5) % 360; glutPostRedisplay(); break; case 'e': elbow = (elbow + 5) % 360; glutPostRedisplay(); break; case 'E': elbow = (elbow - 5) % 360; glutPostRedisplay(); break; case 27: exit(0); break; default: break; } } int main(int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB); glutInitWindowSize(800, 400); glutInitWindowPosition(100, 100); glutCreateWindow(argv[0]); init(); glutDisplayFunc(display); glutReshapeFunc(reshape); glutKeyboardFunc(keyboard); glutMainLoop(); return 0; }

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  • Flipping OpenGL texture

    - by Mk12
    When I load textures from images normally, they are upside down because of OpenGL's coordinate system. What would be the best way to flip them? glScalef(1.0f, -1.0f, 1.0f); vertically flipping the image files manually (in Photoshop) flipping them programatically after loading them (I don't know how) This is the method I'm using to load png textures, in my Utilities.m file (Objective-C): + (GLuint)loadPngTexture:(NSString *)name { CFURLRef textureURL = CFBundleCopyResourceURL( CFBundleGetMainBundle(), (CFStringRef)name, CFSTR("png"), CFSTR("Textures")); NSAssert(textureURL, @"Texture name invalid"); CGImageSourceRef imageSource = CGImageSourceCreateWithURL(textureURL, NULL); NSAssert(imageSource, @"Invalid Image Path."); NSAssert((CGImageSourceGetCount(imageSource) > 0), @"No Image in Image Source."); CFRelease(textureURL); CGImageRef image = CGImageSourceCreateImageAtIndex(imageSource, 0, NULL); NSAssert(image, @"Image not created."); CFRelease(imageSource); NSUInteger width = CGImageGetWidth(image); NSUInteger height = CGImageGetHeight(image); void *data = malloc(width * height * 4); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); NSAssert(colorSpace, @"Colorspace not created."); CGContextRef context = CGBitmapContextCreate( data, width, height, 8, width * 4, colorSpace, kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host); NSAssert(context, @"Context not created."); CGColorSpaceRelease(colorSpace); CGContextDrawImage(context, CGRectMake(0, 0, width, height), image); CGImageRelease(image); CGContextRelease(context); GLuint textureId; glGenTextures(1, &textureId); glBindTexture(GL_TEXTURE_2D, textureId); glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS, GL_TRUE); glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, data); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE_SGIS); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE_SGIS); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); free(data); return textureId; } Also, another thing I was wondering about: If I made a simple 2d game, with pixels mapped to units, would it be alright to set it up so that the origin is in the top-left corner, or would I run in to problems with other things (e.g. text rendering)? Thanks.

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  • OpenGL ES functions not accepting values originating outside of it's view

    - by Josh Elsasser
    I've been unable to figure this out on my own. I currently have an Open GLES setup where a view controller both updates a game world (with a dt), fetches the data I need to render, passes it off to an EAGLView through two structures (built of Apple's ES1Renderer), and draws the scene. Whenever a value originates outside of the Open GL view, it can't be used to either translate objects using glTranslatef, or set up the scene using glOrthof. If I assign a new value to something, it will work - even if it is the exact same number. The two structures I have each contain a variety of floating-point numbers and booleans, along with two arrays. I can log the values from within my renderer - they make it there - but I receive errors from OpenGL if I try to do anything with them. No crashes result, but the glOrthof call doesn't work if I don't set the camera values to anything different. Code used to set up scene: [EAGLContext setCurrentContext:context]; glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer); //clears the color buffer bit glClear(GL_COLOR_BUFFER_BIT); glMatrixMode(GL_PROJECTION); //sets up the scene w/ ortho projection glViewport(0, 0, 320, 480); glLoadIdentity(); glOrthof(320, 0, dynamicData.cam_x2, dynamicData.cam_x1, 1.0, -1.0); glClearColor(1.0, 1.0, 1.0, 1.0); /*error checking code here*/ "dynamicData" (which is replaced every frame) is created within my game simulation. From within my controller, I call a method (w/in my simulation) that returns it, and pass the result on to the EAGLView, which passes it on to the renderer. I haven't been able to come up with a better solution for this - suggestions in this regard would be greatly appreciated as well. Also, this function doesn't work as well (values originate in the same place): glTranslatef(dynamicData.ship_x, dynamicData.ship_y, 0.0); Thanks in advance. Additional Definitions: Structure (declared in a separate header): typedef struct { float ship_x, ship_y; float cam_x1, cam_x2; } dynamicRenderData; Render data getter (and builder) (every frame) - (dynamicData)getDynRenderData { //d_rd is an ivar, zeroed on initialization d_rd.ship_x = mainShip.position.x; d_rd.ship_y = mainShip.position.y; d_rd.cam_x1 = d_rd.ship_x - 30.0f; d_rd.cam_x2 = d_rd.cam_x1 + 480.0f; return d_rd; } Zeroed at start. (d_rd.ship_x = 0;, etc…) Setting up the view. Prototype (GLView): - (void)draw: (dynamicRenderData)dynamicData Prototype (Renderer): - (void)drawView: (dynamicRenderData)dynamicData How it's called w/in the controller: //controller [glview draw: [world getDynRenderData]]; //glview (within draw) [renderer drawView: dynamicData];

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  • iPhone OpenGL scrolling background jumps when texture is drawn for first time

    - by Magnum39
    I have been fighting a problem for a while now and would appreciate any help anybody could give. I have a sprite that moves within a landscape. The sprite remains in the center of the screen and the background moves to simulate that the sprite is moving within the landscape. I have split the landscape into sections so that I only draw the sections of the landscape that I need (are on screen). The Problem: As a new texture section of the screen appears on the screen (is drawn for the first time) the movement jumps. Almost like a frame is missed. I have done some timing experiments and I do not thinks a frame is missed. My processing is well below the 30fps that I have the animation set to. It only happens the first time the texture section is drawn. Is there something extra that is done the first time a texture is drawn? Here is the code: - (void) render{ // Sets up an array of values to use as the sprite vertices. const GLfloat sVerts[] = { -1.6f, -1.6f, 1.6f, -1.6f, -1.6f, 1.6f, 1.6f, 1.6f, }; static const GLfloat sTexCoords[] = { 0.0, 1.0, 1.0, 1.0, 0.0, 0.0, 1.0, 0.0 }; glDisableClientState(GL_COLOR_ARRAY); glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); // Setup opengl to draw the object in correct orientation, size, position, etc glLoadIdentity(); // Enable use of the texture glEnable(GL_TEXTURE_2D); glVertexPointer(2, GL_FLOAT, 0, sVerts); glTexCoordPointer(2, GL_FLOAT, 0, sTexCoords); // draw the texture // set the position of the first tile float xOffset = -4.8; float yOffset = 4.8; int i; int y; int currentTexture = textureA; for(i=0; i<2; i++) { for(y=0; y<2; y++) { // test for the texture tile on the screen if not on screen then do not draw float localX = xOffset+(3.21*y); float localY = yOffset-(3.21*i); float xDiff = monkeyX - localX; float yDiff = monkeyY - localY; if(((xDiff < 3.2) && (xDiff > -3.2)) && ((yDiff <2.7) && (yDiff > -2.7))) { // bind the texture and set the vertex data pointers glBindTexture(GL_TEXTURE_2D, spriteTexture[currentTexture]); // move to draw position for the texture glLoadIdentity(); glTranslatef((localX+self.positionX), (localY+self.positionY), 0.0); //draw the texture glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); } currentTexture++; } } }

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  • optimizing iPhone OpenGL ES fill rate

    - by NateS
    I have an Open GL ES game on the iPhone. My framerate is pretty sucky, ~20fps. Using the Xcode OpenGL ES performance tool on an iPhone 3G, it shows: Renderer Utilization: 95% to 99% Tiler Utilization: ~27% I am drawing a lot of pretty large images with a lot of blending. If I reduce the number of images drawn, framerates go from ~20 to ~40, though the performance tool results stay about the same (renderer still maxed). I think I'm being limited by the fill rate of the iPhone 3G, but I'm not sure. My questions are: How can I determine with more granularity where the bottleneck is? That is my biggest problem, I just don't know what is taking all the time. If it is fillrate, is there anything I do to improve it besides just drawing less? I am using texture atlases. I have tried to minimize image binds, though it isn't always possible (drawing order, not everything fits on one 1024x1024 texture, etc). Every frame I do 10 image binds. This seem pretty reasonable, but I could be mistaken. I'm using vertex arrays and glDrawArrays. I don't really have a lot of geometry. I can try to be more precise if needed. Each image is 2 triangles and I try to batch things were possible, though often (maybe half the time) images are drawn with individual glDrawArrays calls. Besides the images, I have ~60 triangles worth of geometry being rendered in ~6 glDrawArrays calls. I often glTranslate before calling glDrawArrays. Would it improve the framerate to switch to VBOs? I don't think it is a huge amount of geometry, but maybe it is faster for other reasons? Are there certain things to watch out for that could reduce performance? Eg, should I avoid glTranslate, glColor4g, etc? I'm using glScissor in a 3 places per frame. Each use consists of 2 glScissor calls, one to set it up, and one to reset it to what it was. I don't know if there is much of a performance impact here. If I used PVRTC would it be able to render faster? Currently all my images are GL_RGBA. I don't have memory issues. Here is a rough idea of what I'm drawing, in this order: 1) Switch to perspective matrix. 2) Draw a full screen background image 3) Draw a full screen image with translucency (this one has a scrolling texture). 4) Draw a few sprites. 5) Switch to ortho matrix. 6) Draw a few sprites. 7) Switch to perspective matrix. 8) Draw sprites and some other textured geometry. 9) Switch to ortho matrix. 10) Draw a few sprites (eg, game HUD). Steps 1-6 draw a bunch of background stuff. 8 draws most of the game content. 10 draws the HUD. As you can see, there are many layers, some of them full screen and some of the sprites are pretty large (1/4 of the screen). The layers use translucency, so I have to draw them in back-to-front order. This is further complicated by needing to draw various layers in ortho and others in perspective. I will gladly provide additional information if reqested. Thanks in advance for any performance tips or general advice on my problem!

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  • Problem with Freetype and OpenGL

    - by Morgan
    Hey, i'm having a weird issue with drawing text in openGL loaded with the Freetype 2 library. Here is a screenshot of what I'm seeing. http://img203.imageshack.us/img203/3316/freetypeweird.png Here are my code bits for loading and rendering my text. class Font { Font(const String& filename) { if (FT_New_Face(Font::ftLibrary, "arial.ttf", 0, &mFace)) { cout << "UH OH!" << endl; } FT_Set_Char_Size(mFace, 16 * 64, 16 * 64, 72, 72); } Glyph* GetGlyph(const unsigned char ch) { if(FT_Load_Char(mFace, ch, FT_LOAD_RENDER)) cout << "OUCH" << endl; FT_Glyph glyph; if(FT_Get_Glyph( mFace->glyph, &glyph )) cout << "OUCH" << endl; FT_BitmapGlyph bitmap_glyph = (FT_BitmapGlyph)glyph; Glyph* thisGlyph = new Glyph; thisGlyph->buffer = bitmap_glyph->bitmap.buffer; thisGlyph->width = bitmap_glyph->bitmap.width; thisGlyph->height = bitmap_glyph->bitmap.rows; return thisGlyph; } }; The relevant glyph information (width, height, buffer) is stored in the following struct struct Glyph { GLubyte* buffer; Uint width; Uint height; }; And finally, to render it, I have this class called RenderFont. class RenderFont { RenderFont(Font* font) { mTextureIds = new GLuint[128]; mFirstDisplayListId=glGenLists(128); glGenTextures( 128, mTextureIds ); for(unsigned char i=0;i<128;i++) { MakeDisplayList(font, i); } } void MakeDisplayList(Font* font, unsigned char ch) { Glyph* glyph = font->GetGlyph(ch); glBindTexture( GL_TEXTURE_2D, mTextureIds[ch]); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, glyph->width, glyph->height, 0, GL_ALPHA, GL_UNSIGNED_BYTE, glyph->buffer); glNewList(mFirstDisplayListId+ch,GL_COMPILE); glBindTexture(GL_TEXTURE_2D, mTextureIds[ch]); glBegin(GL_QUADS); glTexCoord2d(0,1); glVertex2f(0,glyph->height); glTexCoord2d(0,0); glVertex2f(0,0); glTexCoord2d(1,0); glVertex2f(glyph->width,0); glTexCoord2d(1,1); glVertex2f(glyph->width,glyph->height); glEnd(); glTranslatef(16, 0, 0); glEndList(); } void Draw(const String& text, Uint size, const TransformComponent* transform, const Color32* color) { glEnable(GL_TEXTURE_2D); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glTranslatef(100, 250, 0.0f); glListBase(mFirstDisplayListId); glCallLists(text.length(), GL_UNSIGNED_BYTE, text.c_str()); glDisable(GL_TEXTURE_2D); glDisable(GL_BLEND); glLoadIdentity(); } private: GLuint mFirstDisplayListId; GLuint* mTextureIds; }; Can anybody see anything weird going on here that would cause the garbled text? It's strange because if I change the font size, or the DPI, then some of the letters that display correctly become garbled, and other letters that were garbled before then display correctly.

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  • opengl, Black lines in-between tiles

    - by MiJyn
    When its translated in an integral value (1,2,3, etc....), there are no black lines in-between the tiles, it looks fine. But when it's translated to a non-integral (1.1, 1.5, 1.67), there are small blackish lines between each tile (I'm imagining that it's due to subpixel rendering, right?) ... and it doesn't look pretty =P So... what should I do? This is my image-loading code, by the way: bool Image::load_opengl() { this->id = 0; glGenTextures(1, &this->id); this->bind(); // Parameters... TODO: Should we change this? glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, this->size.x, this->size.y, 0, GL_BGRA, GL_UNSIGNED_BYTE, (void*) FreeImage_GetBits(this->data)); this->unbind(); return true; } I've also tried using: glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); and: glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); Here is my image drawing code: void Image::draw(Pos pos, CROP crop, SCALE scale) { if (!this->loaded || this->id == 0) { return; } // Start position & size Pos s_p; Pos s_s; // End size Pos e_s; if (crop.active) { s_p = crop.pos / this->size; s_s = crop.size / this->size; //debug("%f %f", s_s.x, s_s.y); s_s = s_s + s_p; s_s.clamp(1); //debug("%f %f", s_s.x, s_s.y); } else { s_s = 1; } if (scale.active) { e_s = scale.size; } else if (crop.active) { e_s = crop.size; } else { e_s = this->size; } // FIXME: Is this okay? s_p.y = 1 - s_p.y; s_s.y = 1 - s_s.y; // TODO: Make this use VAO/VBO's!! glPushMatrix(); glTranslate(pos.x, pos.y, 0); this->bind(); glBegin(GL_QUADS); glTexCoord2(s_p.x, s_p.y); glVertex2(0, 0); glTexCoord2(s_s.x, s_p.y); glVertex2(e_s.x, 0); glTexCoord2(s_s.x, s_s.y); glVertex2(e_s.x, e_s.y); glTexCoord2(s_p.x, s_s.y); glVertex2(0, e_s.y); glEnd(); this->unbind(); glPopMatrix(); } OpenGL Initialization code: void game__gl_init() { glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluOrtho2D(0.0, config.window.size.x, config.window.size.y, 0.0); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glDisable(GL_DEPTH_TEST); glEnable(GL_BLEND); glEnable(GL_TEXTURE_2D); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); } Screenshots of the issue:

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  • OpenGL polygons stuck at top left?

    - by user146780
    I'm using theallegro library and through it OpenGL. I enable depth testing, then upon resize I do: glEnable(GL_CULL_FACE); glCullFace(GL_BACK); glEnable(GL_DEPTH_TEST); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glFrustum(0,event.display.width,event.display.height,0,1,300); Then my drawing looks like: float BOX_SIZE = 200.0f; glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glRotatef(0.5, 0, 0.0f, 1.0f); glBegin(GL_QUADS); //Top face glColor3f(1.0f, 1.0f, 0.0f); glNormal3f(0.0, 1.0f, 0.0f); glVertex3f(500 + -BOX_SIZE / 2, BOX_SIZE / 2, -BOX_SIZE / 2); glVertex3f(500 + -BOX_SIZE / 2, BOX_SIZE / 2, BOX_SIZE / 2); glVertex3f(500 + BOX_SIZE / 2, BOX_SIZE / 2, BOX_SIZE / 2); glVertex3f(500 + BOX_SIZE / 2, BOX_SIZE / 2, -BOX_SIZE / 2); //Bottom face glColor3f(1.0f, 0.0f, 1.0f); glNormal3f(0.0, -1.0f, 0.0f); glVertex3f(-BOX_SIZE / 2, -BOX_SIZE / 2, -BOX_SIZE / 2); glVertex3f(BOX_SIZE / 2, -BOX_SIZE / 2, -BOX_SIZE / 2); glVertex3f(BOX_SIZE / 2, -BOX_SIZE / 2, BOX_SIZE / 2); glVertex3f(-BOX_SIZE / 2, -BOX_SIZE / 2, BOX_SIZE / 2); //Left face glNormal3f(-1.0, 0.0f, 0.0f); glColor3f(0.0f, 1.0f, 1.0f); glVertex3f(-BOX_SIZE / 2, -BOX_SIZE / 2, -BOX_SIZE / 2); glVertex3f(-BOX_SIZE / 2, -BOX_SIZE / 2, BOX_SIZE / 2); glColor3f(0.0f, 0.0f, 1.0f); glVertex3f(-BOX_SIZE / 2, BOX_SIZE / 2, BOX_SIZE / 2); glVertex3f(-BOX_SIZE / 2, BOX_SIZE / 2, -BOX_SIZE / 2); //Right face glNormal3f(1.0, 0.0f, 0.0f); glColor3f(1.0f, 0.0f, 0.0f); glVertex3f(BOX_SIZE / 2, -BOX_SIZE / 2, -BOX_SIZE / 2); glVertex3f(BOX_SIZE / 2, BOX_SIZE / 2, -BOX_SIZE / 2); glColor3f(0.0f, 1.0f, 0.0f); glVertex3f(BOX_SIZE / 2, BOX_SIZE / 2, BOX_SIZE / 2); glVertex3f(BOX_SIZE / 2, -BOX_SIZE / 2, BOX_SIZE / 2); glEnd(); glEnable(GL_TEXTURE_2D); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glColor3f(1.0f, 1.0f, 1.0f); glBegin(GL_QUADS); //Front face glNormal3f(0.0, 0.0f, 1.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-BOX_SIZE / 2, -BOX_SIZE / 2, BOX_SIZE / 2); glTexCoord2f(1.0f, 0.0f); glVertex3f(BOX_SIZE / 2, -BOX_SIZE / 2, BOX_SIZE / 2); glTexCoord2f(1.0f, 1.0f); glVertex3f(BOX_SIZE / 2, BOX_SIZE / 2, BOX_SIZE / 2); glTexCoord2f(0.0f, 1.0f); glVertex3f(-BOX_SIZE / 2, BOX_SIZE / 2, BOX_SIZE / 2); //Back face glNormal3f(0.0, 0.0f, -1.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-BOX_SIZE / 2, -BOX_SIZE / 2, -BOX_SIZE / 2); glTexCoord2f(1.0f, 0.0f); glVertex3f(-BOX_SIZE / 2, BOX_SIZE / 2, -BOX_SIZE / 2); glTexCoord2f(1.0f, 1.0f); glVertex3f(BOX_SIZE / 2, BOX_SIZE / 2, -BOX_SIZE / 2); glTexCoord2f(0.0f, 1.0f); glVertex3f(BOX_SIZE / 2, -BOX_SIZE / 2, -BOX_SIZE / 2); glEnd(); glDisable(GL_TEXTURE_2D); //code goes here al_flip_display(); for some reason the cube no matter how I translate it seems to extend from 0,0 and theres always a vertex at 0,0. What have I done wrong? Thanks

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