c - OpenGL 纹理初始化/渲染问题

标签 c cocoa opengl textures

我尝试使用模型类来渲染非 2 的幂纹理，该模型类创建纹理并存储其 ID 和大小(感谢 ADC 和另一个 stackoverflow 成员)，以及创建 VBO 并渲染它的附加代码(以下代码VBO 和渲染用于测试目的，它在我的模型中正确划分)。

当我使用此代码，但删除特定于纹理的代码时，它工作正常。然而，当添加纹理特定代码时，它仅渲染我认为是右下像素的像素，通过尝试多个复杂图像并使用 DigitalColor Meter 检查图像和输出。

我不认为使用此设置时必须显式指定纹理坐标，如果需要，我会如何指定？

主要 OpenGL 代码

    // Create vertex buffer
    GLuint memoryPointer = 0;
    GLuint colourMemoryPointer = 0;

    GLfloat *vertices;
    size_t vertex_size = 0;

    int check = AllocateVertexBuffer(2, 4, &vertices, &vertex_size);
    CDMeshVertexesCreateRectangle(200, 200, vertices);


    // Create colour buffer
    GLfloat *colors;
    size_t color_size;

    int check2 = AllocateVertexBuffer(4, 4, &colors, &color_size);
    CDMeshColorsCreateGrey(1.0, 4, colors);


    // Create texture buffer
    CDTexture *texture = [CDTexture loadPngTexture:@"Rawr"];

    // Allocate the buffer
    glGenBuffers(1, &memoryPointer);
    // Bind the buffer object (tell OpenGL what to use)
    glBindBuffer(GL_ARRAY_BUFFER, memoryPointer);

    // Allocate space for the VBO
    glBufferData(GL_ARRAY_BUFFER, vertex_size, vertices, GL_STATIC_DRAW);


    // Allocate the buffer
    glGenBuffers(1, &colourMemoryPointer);
    // Bind the buffer object (tell OpenGL what to use)
    glBindBuffer(GL_ARRAY_BUFFER, colourMemoryPointer);

    // Allocate space for the VBO
    glBufferData(GL_ARRAY_BUFFER, color_size, colors, GL_STATIC_DRAW);

    glEnableClientState(GL_VERTEX_ARRAY); // Activate vertex coordinates array
    glEnableClientState(GL_COLOR_ARRAY);

    glBindBuffer(GL_ARRAY_BUFFER, memoryPointer);
    glVertexPointer(2, GL_FLOAT, 0, 0);   

    glBindBuffer(GL_ARRAY_BUFFER, colourMemoryPointer);
    glColorPointer(4, GL_FLOAT, 0, 0);

    glBindTexture(GL_TEXTURE_RECTANGLE_ARB, texture.ID);
    glTexCoordPointer(2, GL_FLOAT, 0, 0);

    //[texture render];

    //render
    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

    glDisableClientState(GL_VERTEX_ARRAY); // Deactivate vertex coordinates array
    glDisableClientState(GL_COLOR_ARRAY);

    free(vertices);
    free(colors);

CDTexture loadPngTexture:方法

CFURLRef textureURL = CFBundleCopyResourceURL(CFBundleGetMainBundle(),
                                              (CFStringRef)fileName,
                                              CFSTR("png"),
                                              NULL);

NSAssert(textureURL, @"Texture name invalid");

// Get the image source using a file path
CGImageSourceRef myImageSourceRef = CGImageSourceCreateWithURL(textureURL, NULL);
NSAssert(myImageSourceRef, @"Invalid Image Path.");
NSAssert((CGImageSourceGetCount(myImageSourceRef) > 0), @"No Image in Image Source.");

// Get the image reference using the source reference, -_-
CGImageRef myImageRef = CGImageSourceCreateImageAtIndex (myImageSourceRef, 0, NULL);
NSAssert(myImageSourceRef, @"Image not created.");

// Start gathering data from the image, before releasing it
GLuint myTextureName;
size_t width = CGImageGetWidth(myImageRef);
size_t height = CGImageGetHeight(myImageRef);
CGRect rect = {{0, 0}, {width, height}};
void * myData = calloc(width * 4, height);
CGColorSpaceRef space = CGColorSpaceCreateDeviceRGB();
CGContextRef myBitmapContext = CGBitmapContextCreate (myData,
                                                      width, height, 8,
                                                      width*4, space,
                                                      kCGBitmapByteOrder32Host |
                                                      kCGImageAlphaPremultipliedFirst);

CGColorSpaceRelease(space);
// Flip so that it isn't upside-down
CGContextTranslateCTM(myBitmapContext, 0, height);
CGContextScaleCTM(myBitmapContext, 1.0f, -1.0f);
CGContextSetBlendMode(myBitmapContext, kCGBlendModeCopy);
CGContextDrawImage(myBitmapContext, rect, myImageRef);
CGContextRelease(myBitmapContext);

glEnable(GL_TEXTURE_RECTANGLE_ARB);

// Generate texture buffer
glGenTextures(1, &myTextureName);

// Bind buffer for use
glBindTexture(GL_TEXTURE_RECTANGLE_ARB, myTextureName);

// Set storage methods
glPixelStorei(GL_UNPACK_ROW_LENGTH, width);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

// Set the parameter required for non power of two textures
glTexParameteri(GL_TEXTURE_RECTANGLE_ARB,
                GL_TEXTURE_MIN_FILTER, GL_LINEAR);

// Load the texture data into the buffer
glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, GL_RGBA8, width, height,
             0, GL_BGRA_EXT, GL_UNSIGNED_INT_8_8_8_8_REV, myData);

// Free the data used, as it's now in the buffer
free(myData);

// Return information on texture object
CDTexture *texture = [[CDTexture alloc] init];

texture.ID = myTextureName;
texture.size = NSMakeSize(width, height);

return texture;

更新
我尝试使用纹理指针来定义该区域，这会导致同样的问题。即使没有绑定(bind)和使用指针，它绘制的颜色/纹理也会这样做。我还尝试在使用和渲染之前和之后启用和禁用 GL_TEXTURE_COORD_ARRAY，并导致同样的问题。

除非我做错了什么，否则问题似乎与纹理指针无关。

GLfloat texCoords[8] = {
0.0, 0.0,
0.0, 1.0,
1.0, 1.0,
1.0, 0.0
};

...

glBindBuffer(GL_ARRAY_BUFFER, colourMemoryPointer);
glColorPointer(4, GL_FLOAT, 0, 0);

glBindTexture(GL_TEXTURE_RECTANGLE_ARB, texture.ID);
glTexCoordPointer(2, GL_FLOAT, 0, texCoords);

//[texture render];

//render
glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

更新2
我尝试从 OpenGL 获取错误代码来尝试解决问题，但没有打印任何错误代码。

更新3
我尝试使用不同的方法来获取原始图像数据，并且发生了相同的结果(尽管有一些变色，因为我一定没有使用正确的颜色设置)。 OpenGL 对数据的解释一定是有缺陷的。我已经尝试过 glPixelStorei() 但到目前为止没有任何改变。由于 OpenGL 没有报告任何错误，它必须与数据的程序解释有关，因此我为数据存储方式设置的参数，或者导致仅显示 1 个像素的顶点问题，尽管因此精度，很可能是参数。

原始图像数据的新流程(感谢另一位 stackoverflow 用户)。发布供引用。

 NSBitmapImageRep *theImage;
int bitsPPixel, bytesPRow;
NSSize size;
unsigned char *theImageData;

NSData* imgData = [NSData dataWithContentsOfFile:fileName options:NSUncachedRead error:nil];  // use FileURL

theImage = [NSBitmapImageRep imageRepWithData:imgData]; 


if( theImage != nil )
{
    bitsPPixel = [theImage bitsPerPixel];
    bytesPRow = [theImage bytesPerRow];
    size.width = [theImage pixelsWide];
    size.height = [theImage pixelsHigh];
}

enter code here

更新4
为了提高效率，更改为 GL_TEXTURE_2D。左下角的像素仍然只被渲染。以下是代码的完整顺序:

// Create vertex buffer
    GLuint memoryPointer = 0;
    GLuint colourMemoryPointer = 0;

    GLfloat *vertices;
    size_t vertex_size = 0;

    AllocateVertexBuffer(2, 4, &vertices, &vertex_size);
    CDMeshVertexesCreateRectangle(200, 200, vertices);


    // Create colour buffer
    GLfloat *colors;
    size_t color_size;

    AllocateVertexBuffer(4, 4, &colors, &color_size);
    CDMeshColorsCreateGrey(1.0, 4, colors);

    // Create Texture UV Coordinates
    GLfloat *texture;
    size_t texture_size;
    AllocateVertexBuffer(4, 2, &texture, &texture_size);
    CDMeshVertexesCreateRectangle(1, 1, texture);

    // Create texture buffer
    NSString *fileName = @"Rawr3";

    CFURLRef textureURL = CFBundleCopyResourceURL(CFBundleGetMainBundle(),
                                                  (CFStringRef)fileName,
                                                  CFSTR("png"),
                                                  NULL);

    NSAssert(textureURL, @"Texture name invalid");

    // Get the image source using a file path
    CGImageSourceRef myImageSourceRef = CGImageSourceCreateWithURL(textureURL, NULL);
    NSAssert(myImageSourceRef, @"Invalid Image Path.");
    NSAssert((CGImageSourceGetCount(myImageSourceRef) > 0), @"No Image in Image Source.");

    // Get the image reference using the source reference, -_-
    CGImageRef myImageRef = CGImageSourceCreateImageAtIndex (myImageSourceRef, 0, NULL);
    NSAssert(myImageSourceRef, @"Image not created.");

    // Start gathering data from the image, before releasing it
    GLuint myTextureName;
    size_t width = CGImageGetWidth(myImageRef);
    size_t height = CGImageGetHeight(myImageRef);
    CGRect rect = {{0, 0}, {width, height}};    //Doesnt need fiddling
    void * myData = calloc(width * 4, height); //Fiddled
    CGColorSpaceRef space = CGColorSpaceCreateDeviceRGB();
    CGContextRef myBitmapContext = CGBitmapContextCreate (myData,
                                                          width, height, 8,
                                                          width*4, space,
                                                          kCGBitmapByteOrder32Host |
                                                          kCGImageAlphaPremultipliedFirst);

    CGColorSpaceRelease(space);
    // Flip so that it isn't upside-down
    CGContextTranslateCTM(myBitmapContext, 0, height);
    CGContextScaleCTM(myBitmapContext, 1.0f, -1.0f);
    CGContextSetBlendMode(myBitmapContext, kCGBlendModeCopy);
    CGContextDrawImage(myBitmapContext, rect, myImageRef);
    CGContextRelease(myBitmapContext);

    // Generate texture buffer
    glGenTextures(1, &myTextureName);

    // Bind buffer for use
    glBindTexture(GL_TEXTURE_2D, myTextureName);

    // Set storage methods
    glTexParameteri(GL_TEXTURE_2D,
                    GL_TEXTURE_STORAGE_HINT_APPLE,
                    GL_STORAGE_CACHED_APPLE);

    glPixelStorei(GL_UNPACK_CLIENT_STORAGE_APPLE, GL_TRUE);

    // Set clamping and rendering preferences
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, 
                    GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, 
                    GL_NEAREST);

    // Load the texture data into the buffer
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height,
                 0, GL_BGRA_EXT, GL_UNSIGNED_INT_8_8_8_8_REV, myData);

    glGetError();

    // Free the data used, as it's now in the buffer
    free(myData);

    // Return information on texture object
    CDTexture *textureObj = [[CDTexture alloc] init];

    textureObj.ID = myTextureName;
    textureObj.size = NSMakeSize(width, height);

    // Allocate the buffer
    glGenBuffers(1, &memoryPointer);
    // Bind the buffer object (tell OpenGL what to use)
    glBindBuffer(GL_ARRAY_BUFFER, memoryPointer);

    // Allocate space for the VBO
    glBufferData(GL_ARRAY_BUFFER, vertex_size, vertices, GL_STATIC_DRAW);


    // Allocate the buffer
    glGenBuffers(1, &colourMemoryPointer);
    // Bind the buffer object (tell OpenGL what to use)
    glBindBuffer(GL_ARRAY_BUFFER, colourMemoryPointer);

    // Allocate space for the VBO
    glBufferData(GL_ARRAY_BUFFER, color_size, colors, GL_STATIC_DRAW);

    glEnableClientState(GL_VERTEX_ARRAY); // Activate vertex coordinates array
    glEnableClientState(GL_COLOR_ARRAY);
    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
    glEnable(GL_TEXTURE_2D);

    glBindBuffer(GL_ARRAY_BUFFER, memoryPointer);
    glVertexPointer(2, GL_FLOAT, 0, 0);   

    glBindBuffer(GL_ARRAY_BUFFER, colourMemoryPointer);
    glColorPointer(4, GL_FLOAT, 0, 0);

    glBindTexture(GL_TEXTURE_2D, textureObj.ID);
    glTexCoordPointer(2, GL_FLOAT, 0, texture);

    GetGLError();

    //render
    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

    glDisableClientState(GL_VERTEX_ARRAY); // Deactivate vertex coordinates array
    glDisableClientState(GL_COLOR_ARRAY);
    glDisableClientState(GL_TEXTURE_COORD_ARRAY);
    glDisable(GL_TEXTURE_2D);

    glDeleteBuffers(1, &memoryPointer);
    glDeleteBuffers(1, &colourMemoryPointer);
    GLuint texID = textureObj.ID;
    glDeleteBuffers(1, &texID);

    free(vertices);
    free(colors);
    free(texture);


}

更新5 从 glTexImage2D() 中，即使我没有绑定(bind)纹理并为其添加坐标，它也会渲染纹理的左下角像素，这看起来很奇怪，因为它应该使用 glTexCoordPointer() 来绘制。

更新6 可能是最后一次更新，使用了纹理初始化代码和另一种更多的“手动”绘图技术，并且效果很好。我已经删除了苹果特有的元素。当从此代码中删除颜色 VBO 和指针时，由于某些奇怪的原因仍然会呈现一个白色框。问题出在 VBO 上，但我不明白为什么。 GL_TEXTURE_RECTANGLE_ARB 目前仅用于我的彩色纹理，当此问题解决后将进行更改。

// Create vertex buffer
    GLuint memoryPointer = 0;
    GLuint colourMemoryPointer = 0;

    GLfloat *vertices;
    size_t vertex_size = 0;

    AllocateVertexBuffer(2, 4, &vertices, &vertex_size);
    CDMeshVertexesCreateRectangle(200, 200, vertices);

    GetGLError();

    // Create colour buffer
    GLfloat *colors;
    size_t color_size;

    AllocateVertexBuffer(4, 4, &colors, &color_size);
    CDMeshColorsCreateGrey(0.4, 4, colors);

    // Allocate the buffer
    glGenBuffers(1, &memoryPointer);
    glBindBuffer(GL_ARRAY_BUFFER, memoryPointer);
    glBufferData(GL_ARRAY_BUFFER, vertex_size, vertices, GL_STATIC_DRAW);

    // Allocate the buffer
    glGenBuffers(1, &colourMemoryPointer);
    glBindBuffer(GL_ARRAY_BUFFER, colourMemoryPointer);
    glBufferData(GL_ARRAY_BUFFER, color_size, colors, GL_STATIC_DRAW);

    // Enable client states for drawing the various arrays
    glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_COLOR_ARRAY);
    glEnableClientState(GL_TEXTURE_COORD_ARRAY);

    // Bind each buffer and use the VBO's to draw (apart from the texture buffer)
    glBindBuffer(GL_ARRAY_BUFFER, memoryPointer);
    glVertexPointer(2, GL_FLOAT, 0, 0);   

    glBindBuffer(GL_ARRAY_BUFFER, colourMemoryPointer);
    glColorPointer(4, GL_FLOAT, 0, 0);

    glBindTexture(GL_TEXTURE_RECTANGLE_ARB, myTextureName); //
    glTexCoordPointer(2, GL_FLOAT, 0, texture);

    //render
    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

    // Disale client states as were done with them.
    glDisableClientState(GL_VERTEX_ARRAY);
    glDisableClientState(GL_COLOR_ARRAY);
    glDisableClientState(GL_TEXTURE_COORD_ARRAY);
    glDisable(GL_TEXTURE_RECTANGLE_ARB);

    GetGLError();

    // Delete buffers to avoid problems
    glDeleteBuffers(1, &memoryPointer);
    glDeleteBuffers(1, &colourMemoryPointer);
    glDeleteBuffers(1, &myTextureName);

    free(vertices);
    free(colors);
    free(texture);

最佳答案

当然，您必须提供纹理坐标。作为顶点属性 vector 的一部分，或者通过生成它们(在着色器中)。但是你必须以某种方式提供纹理坐标，你无法绕过这个。

关于c - OpenGL 纹理初始化/渲染问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/6708994/

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