iOS OpenGL ES-在模拟器和设备上的不同纹理行为 [英] iOS OpenGL ES - Different texture behaviour on simulator and device
问题描述
我正在使用OpenGL ES加载纹理，以下是我的代码.
I'm loading textures using OpenGL ES, the below is my code.
图形由2个相同大小的纹理组成，包括停止"按钮和后面的蓝色发光.
The graphic is made up of 2 textures of the same size, the stop button and the blue glow behind.
下面的第一个图形是使用xCode中的iPad模拟器拍摄的，第二个图形是在实际设备上拍摄的.当我从Illustrator导出图形时，第一个图形是正确的输出.但是，当我在iPad上加载程序时，它会显示第二张图形.停止按钮后面的蓝色光似乎已经变小了.为什么会这样呢?
The first graphic below was taken using the iPad simulator in xCode, and the 2nd on the actual device. The 1st graphic is the correct output as I exported the graphics from Illustrator. However, when I loaded the program on the iPad, it gives me the 2nd graphic. It seems somehow that the blue light texture behind the stop button has become smaller. Why is this so?
我可以通过增大蓝色光的纹理来进行补偿，但这并不是正确的，因为它在Illustrator中的外观应该是第一幅图形.
I can compensate by making the blue light texture bigger, but it wouldn't be right as the way it is supposed to look in Illustrator is the 1st graphic.
这是我的代码.
//
// OpenGLES_Ch3_4ViewController.m
// OpenGLES_Ch3_4
//
#import "OpenGLES_Ch3_4ViewController.h"
#import "AGLKVertexAttribArrayBuffer.h"
#import "AGLKContext.h"
#define Y_POS 1.0
#define ASPECT_RATIO 0.75f
#define SIZE 0.8
@implementation OpenGLES_Ch3_4ViewController
@synthesize baseEffect;
@synthesize vertexBuffer;
@synthesize textureInfo0;
@synthesize textureInfo1;
/////////////////////////////////////////////////////////////////
// This data type is used to store information for each vertex
typedef struct {
GLKVector3 positionCoords;
GLKVector2 textureCoords;
}
SceneVertex;
/////////////////////////////////////////////////////////////////
// Define vertex data for a triangle to use in example
//static const SceneVertex vertices[] =
static const SceneVertex vertices[] =
{
{{-1.0f*SIZE, -ASPECT_RATIO*SIZE, 0.0f}, {0.0f, 0.0f}}, // first triangle
{{ 0.0f*SIZE, -ASPECT_RATIO*SIZE, 0.0f}, {1.0f, 0.0f}},
{{-1.0f*SIZE, 0.0f*SIZE, 0.0f}, {0.0f, 1.0f}},
{{ 0.0f*SIZE, -ASPECT_RATIO*SIZE, 0.0f}, {1.0f, 0.0f}}, // second triangle
{{-1.0f*SIZE, 0.0f*SIZE, 0.0f}, {0.0f, 1.0f}},
{{ 0.0f*SIZE, 0.0f*SIZE, 0.0f}, {1.0f, 1.0f}},
};
/////////////////////////////////////////////////////////////////
// Called when the view controller's view is loaded
// Perform initialization before the view is asked to draw
- (void)viewDidLoad
{
[super viewDidLoad];
// Verify the type of view created automatically by the
// Interface Builder storyboard
GLKView *view = (GLKView *)self.view;
NSAssert([view isKindOfClass:[GLKView class]],
@"View controller's view is not a GLKView");
// Create an OpenGL ES 2.0 context and provide it to the
// view
view.context = [[AGLKContext alloc]
initWithAPI:kEAGLRenderingAPIOpenGLES2];
// Make the new context current
[AGLKContext setCurrentContext:view.context];
// Create a base effect that provides standard OpenGL ES 2.0
// shading language programs and set constants to be used for
// all subsequent rendering
self.baseEffect = [[GLKBaseEffect alloc] init];
self.baseEffect.useConstantColor = GL_TRUE;
self.baseEffect.constantColor = GLKVector4Make(
1.0f, // Red
1.0f, // Green
1.0f, // Blue
1.0f);// Alpha
// Set the background color stored in the current context
((AGLKContext *)view.context).clearColor = GLKVector4Make(
0.0f, // Red
0.0f, // Green
0.0f, // Blue
1.0f);// Alpha
// Create vertex buffer containing vertices to draw
self.vertexBuffer = [[AGLKVertexAttribArrayBuffer alloc]
initWithAttribStride:sizeof(SceneVertex)
numberOfVertices:sizeof(vertices) / sizeof(SceneVertex)
bytes:vertices
usage:GL_STATIC_DRAW];
// Setup texture0
CGImageRef imageRef0 =
[[UIImage imageNamed:@"stoplight_full.png"] CGImage];
self.textureInfo0 = [GLKTextureLoader
textureWithCGImage:imageRef0
options:[NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES],
GLKTextureLoaderOriginBottomLeft, nil]
error:NULL];
self.textureInfo0_2 = [GLKTextureLoader
textureWithCGImage:imageRef0
options:nil
error:NULL];
// Setup texture1
CGImageRef imageRef1 =
[[UIImage imageNamed:@"stop_button.png"] CGImage];
self.textureInfo1 = [GLKTextureLoader
textureWithCGImage:imageRef1
options:[NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES],
GLKTextureLoaderOriginBottomLeft, nil]
error:NULL];
self.textureInfo1_2 = [GLKTextureLoader
textureWithCGImage:imageRef1
options:nil
error:NULL];
// Enable fragment blending with Frame Buffer contents
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
}
/////////////////////////////////////////////////////////////////
// GLKView delegate method: Called by the view controller's view
// whenever Cocoa Touch asks the view controller's view to
// draw itself. (In this case, render into a frame buffer that
// shares memory with a Core Animation Layer)
- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect
{
// Clear back frame buffer (erase previous drawing)
[(AGLKContext *)view.context clear:GL_COLOR_BUFFER_BIT];
[self.vertexBuffer prepareToDrawWithAttrib:GLKVertexAttribPosition
numberOfCoordinates:3
attribOffset:offsetof(SceneVertex, positionCoords)
shouldEnable:YES];
[self.vertexBuffer prepareToDrawWithAttrib:GLKVertexAttribTexCoord0
numberOfCoordinates:2
attribOffset:offsetof(SceneVertex, textureCoords)
shouldEnable:YES];
self.baseEffect.texture2d0.name = self.textureInfo0.name;
self.baseEffect.texture2d0.target = self.textureInfo0.target;
[self.baseEffect prepareToDraw];
// Draw triangles using the vertices in the
// currently bound vertex buffer
[self.vertexBuffer drawArrayWithMode:GL_TRIANGLES
startVertexIndex:0
numberOfVertices:sizeof(vertices) / sizeof(SceneVertex)];
self.baseEffect.texture2d0.name = self.textureInfo1.name;
self.baseEffect.texture2d0.target = self.textureInfo1.target;
[self.baseEffect prepareToDraw];
// Draw triangles using currently bound vertex buffer
[self.vertexBuffer drawArrayWithMode:GL_TRIANGLES
startVertexIndex:0
numberOfVertices:sizeof(vertices) / sizeof(SceneVertex)];
}
推荐答案
对我来说，第二个纹理看起来并不小，只是较暗. 您的笔记本电脑和iPad最有可能具有不同的伽玛值的显示器.
To me, the second texture does not look smaller, just dimmer. Your laptop and iPad most likely have displays with different gammas.
There are many ways to correct for gamma, a terrific introduction is provided here.
值得注意的是，如今，许多现代显卡也可以为您完成此操作，但据我所知，到目前为止，OpenGL ES尚不支持它:
It is worth noting many modern cards can do it for you these days too, but so far unsupported on OpenGL ES as far as I know: sRGB Color Formats.
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