土壤-获得图像尺寸

SOIL - Getting Image Dimensions

本文关键字：图像 土壤      更新时间：2023-10-16

我决定使用SOIL来加载图像，以便在我的项目中使用OpenGL。我有这个方法，它加载一个图像并返回一个GLTexture，这是一个结构体，包含一个glint纹理和两个int宽度和高度:

GLTexture loadTexture(const char *filePath) {
GLTexture texture = {};
int width;
int height;
unsigned char *data;
//Load Image File Directly into an OpenGL Texture
texture.id = SOIL_load_OGL_texture
    (
    filePath,
    SOIL_LOAD_AUTO,
    SOIL_CREATE_NEW_ID,
    SOIL_FLAG_MIPMAPS | SOIL_FLAG_INVERT_Y | SOIL_FLAG_NTSC_SAFE_RGB | SOIL_FLAG_COMPRESS_TO_DXT
    );
//Error Checking (Load Process)
if (texture.id == 0) {
    fatalError("SOIL Loading Error!");
}
//Generate and Bind Texture
glGenTextures(1, &(texture.id));
glBindTexture(GL_TEXTURE_2D, texture.id);
//Get Width, Height and Data of Image
glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, &width);
glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_HEIGHT, &height);
glGetTexImage(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, &data);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, &data);
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_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glGenerateMipmap(GL_TEXTURE_2D);
//Unbind Texture
glBindTexture(GL_TEXTURE_2D, 0);
//Return Texture
texture.width = width;
texture.height = height;
return texture;

}

据我所知，glGetTexLevelParameteriv()应该返回绑定到宽度和高度的纹理的宽度，但每当我加载图像时，这返回0.

我应该填充宽度和高度作为方法的参数，还是有可能通过OpenGL获得它们?

由SOIL_load_OGL_texture生成的纹理id在

中被覆盖
glGenTextures(1, &(texture.id));

line (glGenTextures创建一个新的纹理并将id存储在&(texture.id)中)。之后的所有操作都在新创建的纹理上工作。因为这个新纹理是空的，所以宽度和高度都是0。

我不确定你想在这里实现什么，但如果你只想加载纹理，那么这段代码可能会起作用:

texture.id = SOIL_load_OGL_texture    (...);
//Error Checking (Load Process)
if (texture.id == 0) {
    fatalError("SOIL Loading Error!");
}
//Just bind and do not create a new texture
glBindTexture(GL_TEXTURE_2D, texture.id);
glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, &width);
glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_HEIGHT, &height);
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_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glGenerateMipmap(GL_TEXTURE_2D);
//Unbind Texture
glBindTexture(GL_TEXTURE_2D, 0);
//Return Texture
texture.width = width;
texture.height = height;
return texture;
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