我在 Xcode 中修改了 OpenGL es 2.0 模板,将那个小盒子渲染为屏幕外纹理 (50*50),然后重置视口并使用全屏四边形将纹理渲染到屏幕上。但是 FPS 下降幅度很大,以至于出现了明显的滞后(大约 10 个)。
我知道 iPad 在填充率方面存在问题,但这似乎并不正确。我只使用了一个 FBO,并在循环中更改了纹理和渲染缓冲区之间的颜色附件。这有什么影响吗?
此外,我正在编写一个音频可视化器(如 Windows Media Player 中的那个),在 OpenGL 中编辑像素值。有什么建议么?
这是代码:
//implement the texture in -(id)init
glGenTextures(1, &ScreenTex);
glBindTexture(GL_TEXTURE_2D, ScreenTex);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, texSize, texSize, 0, GL_RGB, GL_UNSIGNED_BYTE, nil);
//And in the render loop
//draw to the texture
glViewport(0, 0, texSize, texSize);
glBindTexture(GL_TEXTURE_2D, ScreenTex);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, ScreenTex, 0);
glClear(GL_COLOR_BUFFER_BIT);
glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, 0, 0, squareVertices);
glUniform1i(Htunnel, 0);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
//switch to render to render buffer here
glViewport(0, 0, backingWidth, backingHeight);
glBindRenderbuffer(GL_RENDERBUFFER, colorRenderbuffer);
glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER,colorRenderbuffer);
glClear(GL_COLOR_BUFFER_BIT);
glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, 0, 0, texVertices);
glUniform1i(Htunnel, 1);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
//vertex shader
void main()
{
if (tunnel==0) {
gl_Position = position;
gl_Position.y += sin(translate) / 2.0;
colorVarying = color;
}else {
f_texCoord = v_texCoord;
gl_Position = position;
}
}
//frag shader
void main()
{
if (tunnel==0) {
gl_FragColor = colorVarying;
} else {
gl_FragColor = texture2D(s_texture, f_texCoord);
}
}