iPhone中的背景纹理图像在OpenGL ES中使用失真绘制

Question

我在我的 iPhone 应用程序中渲染背景纹理时遇到问题。下图显示了问题：

http://www.tojamgames.com/wp-content/uploads/2010/09/background_layer1.png

tojamgames.com/wp-content/uploads/2010/09/IMG_0246.png（无法将其设为链接，抱歉）

第一个是正确的图像，第二个是用OpenGL ES绘制的（是的，它更小，我在照片编辑器中手动裁剪它以删除一些游戏UI界面。你可以得到不过，失真效果的想法很清楚）。显然，渲染纹理上的扭曲线并不理想。这是我设置 opengl、加载纹理和渲染图像的代码 - 任何帮助都会很棒！对不起，这很长，但我正在尝试提供尽可能多的信息：-P

OpenGL 初始化：

glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_FASTEST);
glShadeModel(GL_FLAT);
glDisable(GL_DITHER);
glDisable(GL_LIGHTING);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrthof(0, screenBounds.size.width, 0, screenBounds.size.height, -1, 1);

glMatrixMode(GL_MODELVIEW);
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_BLEND_SRC);
glEnableClientState(GL_VERTEX_ARRAY);

glDisable(GL_DEPTH_TEST);

glClearColor(1.0f, 1.0f, 1.0f, 0.0f);

纹理加载：

glGenTextures(1, &_name);
glGetIntegerv(GL_TEXTURE_BINDING_2D, &saveName);
glBindTexture(GL_TEXTURE_2D, _name);

glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);

绘画场景

[EAGLContext setCurrentContext:context];
glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer);


glViewport(0, 0, screenBounds.size.width , screenBounds.size.height);

// texture images have pre-multiplied alpha, so use this blend function
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);

[backgroundImage drawAtPoint:CGPointMake(0,0)];

// more game-specific stuff you don't need to see :-P

glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);
[context presentRenderbuffer:GL_RENDERBUFFER_OES];

最后，绘制图像本身（在 drawAtPoint 方法调用中）

// grab texture coordinates - maxS & maxT are the width & height in the POT texture
// that contain our NPOT image
GLfloat  coordinates[] = {  0,  0,
_maxS,         0,
    0,  _maxT,
_maxS,         _maxT  };

GLfloat screenHeight = [[UIScreen mainScreen] bounds].size.height;

// adjust the vertices of the quad so they're contained within the bounding rect of the
// image in the game, subtracting from screenHeight to invert the OpenGL coordinate system
GLfloat vertices[] = { rect.origin.x, screenHeight - rect.origin.y, 0.0,
rect.origin.x + rect.size.width, screenHeight - rect.origin.y, 0.0,
rect.origin.x, screenHeight - (rect.origin.y + rect.size.height), 0.0,
rect.origin.x + rect.size.width, screenHeight - (rect.origin.y + rect.size.height), 0.0 };

glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glEnable(GL_TEXTURE_2D);

glBindTexture(GL_TEXTURE_2D, _name);
glVertexPointer(3, GL_FLOAT, 0, vertices);
glTexCoordPointer(2, GL_FLOAT, 0, coordinates);

glEnable(GL_BLEND);

glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

glDisable(GL_BLEND);

glDisable(GL_TEXTURE_2D);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);

再次，对不起，这很长，但希望它提供了足够的东西，有人可以看到我搞砸了！非常感谢！

汤姆

Answer 1

这看起来像颜色量化。您的视图的kEAGLDrawablePropertyColorFormat 属性是否设置为kEAGLColorFormatRGB565？如果是这样，请查看将其更改为 kEAGLColorFormatRGBA8 是否可以解决您的问题。