我希望可以使用mipmapping来渲染IOSurface
纹理。
我正在从IOSurface
生成一个OpenGL
纹理,步骤如下:
let error = CGLTexImageIOSurface2D(context.cglContextObj!,
GLenum(GL_TEXTURE_RECTANGLE_ARB),GLenum(GL_RGBA), GLsizei(width), GLsizei(height),
GLenum(GL_BGRA), GLenum(GL_UNSIGNED_INT_8_8_8_8_REV), surface!, 0)
并使用简单的片段着色器进行渲染:
#version 120
uniform sampler2DRect texture;
varying vec2 texCoord;
uniform vec2 size;
void main(){
vec4 tex = texture2DRect(texture, texCoord*size);
gl_FragColor = tex;
}
这个功能很好,但不幸的是,当缩小查看时,纹理没有被贴图处理,显得很粗糙/像素化。进一步研究后,发现不仅
IOSurface
支持的纹理目标只限于GL_TEXTURE_RECTANGLE_ARB
,而且也不支持贴图处理。好吧,我的最佳替代方案似乎是:
- 将
GL_TEXTURE_RECTANGLE_ARB
纹理复制到GL_TEXTURE_2D
纹理中 - 为这个新纹理生成贴图处理
glCopyImageSubData
。相反,我基于此答案来完成步骤1:How to copy texture1 to texture2 efficiently?
现在我的完整代码如下:if !hasCreatedTexture {
glGenTextures(1, &texture);
glGenTextures(1, &arbTexture);
glGenFramebuffers(1, &fbo)
hasCreatedTexture = true
}
glEnable(GLenum(GL_TEXTURE_RECTANGLE_ARB))
glBindTexture(GLenum(GL_TEXTURE_RECTANGLE_ARB), arbTexture)
let error = CGLTexImageIOSurface2D(context.cglContextObj!, GLenum(GL_TEXTURE_RECTANGLE_ARB), GLenum(GL_RGBA), GLsizei(width), GLsizei(height), GLenum(GL_BGRA), GLenum(GL_UNSIGNED_INT_8_8_8_8_REV), surface!, 0)
glBindFramebuffer(GLenum(GL_FRAMEBUFFER), fbo);
glFramebufferTexture2D(GLenum(GL_READ_FRAMEBUFFER), GLenum(GL_COLOR_ATTACHMENT0),
GLenum(GL_TEXTURE_RECTANGLE_ARB), arbTexture, 0);
glFramebufferTexture2D(GLenum(GL_DRAW_FRAMEBUFFER), GLenum(GL_COLOR_ATTACHMENT1),
GLenum(GL_TEXTURE_2D), texture, 0);
glDrawBuffer(GLenum(GL_COLOR_ATTACHMENT1));
glBlitFramebuffer(0, 0, GLint(width), GLint(height), 0, 0, GLint(width), GLint(height), GLbitfield(GL_COLOR_BUFFER_BIT), GLenum(GL_NEAREST));
glBindTexture(GLenum(GL_TEXTURE_2D), texture)
我将我的着色器更改为支持GL_TEXTURE_2D
:
#version 120
uniform sampler2D texture;
varying vec2 texCoord;
void main(){
vec4 tex = texture2D(texture, texCoord);
gl_FragColor = tex;
}
我现在遇到了困难。图片全部是黑色,我不知道为什么它不能正常显示。
我尝试查看像素数据,如下所示:
var pixelData = UnsafeMutablePointer<GLubyte>(allocatingCapacity: Int(width * height * 4))
glGetTexImage(GLenum(GL_TEXTURE_2D), 0, GLenum(GL_BGRA),
GLenum(GL_UNSIGNED_INT_8_8_8_8_REV), pixelData)
print(NSData(bytes: pixelData, length: 50000).description)
这都是零。我的方法有问题吗?还是这个问题特别与处理基于IOSurface
的纹理有关?