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POTrouble Displaying Textures OpenGL ES 1.1
 

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  1. POTrouble Displaying Textures OpenGL ES 1.1
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    <p>I'm working on a simple little game for the iPhone, and I'd like to use textures, however I can't quite seem to get it working...</p> <p>After some research I found <a href="http://mobile.dzone.com/news/loading-images-opengl-iphone" rel="nofollow">this page</a> and <a href="http://iphonedevelopment.blogspot.com/2009/05/opengl-es-from-ground-up-part-6_25.html" rel="nofollow">this site</a>. Both are great references, and taught me a little bit about textures, however, after loading a texture using either function I can't get the texture displayed, here's what my code looks like:</p> <p><strong>Very Simple Texture Display Function</strong> (not working)</p> <pre><code>void drawTexture(GLuint texture, float x, float y, float w, float h) { glBindTexture(GL_TEXTURE_2D,texture); GLfloat box[] = {x,y+h, x+w,y+h, x,y, x+w,y}; GLfloat tex[] = {0,0, 1,0, 1,1, 0,1}; glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); glVertexPointer(2, GL_FLOAT, 0,box); glTexCoordPointer(2, GL_FLOAT, 0, tex); glDrawArrays(GL_TRIANGLE_STRIP,0,4); glDisableClientState(GL_VERTEX_ARRAY); glDisableClientState(GL_TEXTURE_COORD_ARRAY); } </code></pre> <p>Normally, I'd not create an array every single frame only to display an image, but this is just an example. When I run this function, I get nothing. Blank- no image, nothing (unless of course I'd previously enabled a color array and hadn't disabled it afterwards)</p> <p><strong>Second Simple Display Function</strong> (this one uses a quick little class)</p> <pre><code>void draw_rect(RectObject* robj){ glVertexPointer(2, GL_FLOAT, 0, [robj vertices]); glEnableClientState(GL_VERTEX_ARRAY); glColorPointer(4, GL_UNSIGNED_BYTE, 0, [robj colors]); glEnableClientState(GL_COLOR_ARRAY); if ([robj texture] != -1){ glEnable(GL_TEXTURE_COORD_ARRAY); glEnable(GL_TEXTURE_2D); glClientActiveTexture([robj texture]); glTexCoordPointer(2, GL_FLOAT, 0, defaultTexCoord); glBindTexture(GL_TEXTURE_2D, [robj texture]); } glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); glDisable(GL_TEXTURE_2D); glDisable(GL_TEXTURE_COORD_ARRAY); } </code></pre> <p>This function on the other hand, does change the display, instead of outputting the texture however it outputs a black square...</p> <p><strong>Setup Background</strong></p> <p>In my init function I'm calling </p> <pre><code>glEnable(GL_TEXTURE_2D); glEnable(GL_BLEND); glBlendFunc(GL_ONE, GL_SRC_COLOR); </code></pre> <p><strong>Two LONG Texture Loading Functions</strong></p> <pre><code>struct Texture2D LoadImage(NSString* path) { struct Texture2D tex; tex.texture = -1; // Id for texture GLuint texture; // Generate textures glGenTextures(1, &amp;texture); // Bind it glBindTexture(GL_TEXTURE_2D, texture); // Set a few parameters to handle drawing the image // at lower and higher sizes than original 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_GENERATE_MIPMAP, GL_TRUE); //NSString *path = [[NSString alloc] initWithUTF8String:imagefile.c_str()]; path = [[NSBundle mainBundle] pathForResource:path ofType:@""]; NSData *texData = [[NSData alloc] initWithContentsOfFile:path]; UIImage *image = [[UIImage alloc] initWithData:texData]; if (image == nil) return tex; // Get Image size GLuint width = CGImageGetWidth(image.CGImage); GLuint height = CGImageGetHeight(image.CGImage); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); // Allocate memory for image void *imageData = malloc( height * width * 4 ); CGContextRef imgcontext = CGBitmapContextCreate( imageData, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big ); CGColorSpaceRelease( colorSpace ); CGContextClearRect( imgcontext, CGRectMake( 0, 0, width, height ) ); CGContextTranslateCTM( imgcontext, 0, height - height ); CGContextDrawImage( imgcontext, CGRectMake( 0, 0, width, height ), image.CGImage ); // Generate texture in opengl glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData); // Release context CGContextRelease(imgcontext); // Free Stuff free(imageData); [image release]; [texData release]; // Create and return texture tex.texture=texture; tex.width=width; tex.height=height; return tex; } GLuint makeTexture(NSString* path){ GLuint texture[1]={-1}; glGenTextures(1, texture); glBindTexture(GL_TEXTURE_2D, texture[0]); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); path = [[NSBundle mainBundle] pathForResource:path ofType:@"png"]; NSData *texData = [[NSData alloc] initWithContentsOfFile:path]; UIImage *image = [[UIImage alloc] initWithData:texData]; if (image == nil) NSLog(@"Do real error checking here"); GLuint width = CGImageGetWidth(image.CGImage); GLuint height = CGImageGetHeight(image.CGImage); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); void *imageData = malloc( height * width * 4 ); CGContextRef context = CGBitmapContextCreate( imageData, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big ); CGColorSpaceRelease( colorSpace ); CGContextClearRect( context, CGRectMake( 0, 0, width, height ) ); CGContextTranslateCTM( context, 0, height - height ); CGContextDrawImage( context, CGRectMake( 0, 0, width, height ), image.CGImage ); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, imageData); CGContextRelease(context); free(imageData); [image release]; [texData release]; return texture[0]; } </code></pre> <p>If you could point me in the right direction it would be much appreciated.</p>
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