OpenGL ES 1.0 中的“glTexEnv”、“glColor4x”和“glBlendFunc”有何关系？
我正在查看 SurfaceFlinger，即在 Android 中进行组合的代码，并且我很难理解一些 OpenGL ES 1.0 调用，因为我只编写了 ES 2.0 代码。
这是我感兴趣的代码片段：
glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glColor4x(0x10000, 0x10000, 0x10000, 0x10000);
glEnable(GL_BLEND);
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
它应该做的是将纹理混合到缓冲区中。
为什么需要 glTextEnvx 和 glColor4x 调用？ glBlendFunc 不足以实现混合吗？
我知道我的问题很天真，但即使在阅读文档。
I'm looking at SurfaceFlinger, i.e. the the code that is doing the composition in Android, and I have trouble understanding some of the OpenGL ES 1.0 calls as I've only programmed ES 2.0 code.
Here goes the piece of code that interests me:
glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glColor4x(0x10000, 0x10000, 0x10000, 0x10000);
glEnable(GL_BLEND);
glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
What it is supposed to be doing is blending a texture into the buffer.
Why does one need the glTextEnvx and glColor4x calls? Isn't glBlendFunc enough for achieving blending?
I know my question is naive, but I still don't understand what is glTexEnvx for even after reading the docs.
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glTexEnv()设置纹理环境模式。GL_REPLACE告诉渲染器跳过当前颜色（例如，来自glColor4()），而是告诉渲染器对每个相应像素使用纹理的颜色。如果您使用GL_MODULATE而不是GL_REPLACE，那么当渲染器设置像素的颜色。您的
glColor4()调用不应执行任何可以在您的对象上看到的操作（使用GL_REPLACE时）。关于
glBlendFunc()参数：GL_ONE使用来自传入基元的当前颜色，我们将其称为源。GL_ONE_MINUS_SRC_ALPHA将目标（帧缓冲区中当前存储的像素）乘以（1 - 源 Alpha 值）。通常，当您不使用纹理时，当
glColor4()包含 alpha 值（其中 1 等于完全不透明，0 等于完全透明）时，您可以从 color 基元实现透明效果。glTexEnv()sets the texture environment mode.GL_REPLACEtells the renderer to skip the current color (for example, fromglColor4()) and instead tells the renderer to use your texture's colors for every corresponding pixel. If you, instead ofGL_REPLACE, useGL_MODULATE, then yourglColor4()call will be included together with the texture's colors when the renderer sets a pixel's color.Your
glColor4()call shouldn't be doing anything (when usingGL_REPLACE) that can be seen on your object.About your
glBlendFunc()arguments:GL_ONEis using the current color that comes from your incoming primitive, which we call source.GL_ONE_MINUS_SRC_ALPHAis multiplying the destination (which is the currently stored pixel in the frame buffer) by (1 - source alpha value).Normally, when you're not using textures, you achieve a transparent effect from color primitives when the
glColor4()contains an alpha value where 1 equals fully opaque and 0 fully transparent.