如何在OpenGL ES 2.0中实现glOrthof [英] How to achieve glOrthof in OpenGL ES 2.0

问题描述

我正在尝试将我的 OpenGL ES 1 应用程序转换为 OpenGL ES 2 应用程序以便能够使用着色器。现在我使用glOrthof函数来创建一个真实大小的视口，这样我就可以将顶点放在OpenGL视图中的实际像素上。

I am trying to convert my OpenGL ES 1 application to a OpenGL ES 2 application to be able to use Shaders. Now I use the glOrthof function to have a "real sized viewport" so I can place the vertices at the "actual" pixel in the OpenGL View.

glOrthof(0, _frame.size.width, _frame.size.height, 0, -1, 1);

我无法在 OpenGL ES 2中找到如何实现这一点/ code>，是否有人可以告诉我该怎么做？

I am having trouble finding out how to achieve this in OpenGL ES 2, is there anyone who can show me how to do this?

如果没有，是否有人有一个良好的 OpenGL ES 1到OpenGL ES 2 教程/解释？

If not, does anyone have a link to a good OpenGL ES 1 to OpenGL ES 2 tutorial/explanation?

推荐答案

glOrtho 方法除了创建一个新矩阵并将当前投影矩阵乘以此矩阵外别无其他。使用OpenGL ES 2.0，您必须自己管理矩阵。为了复制 glOrtho 行为，您需要在顶点着色器中为投影矩阵制作一个统一，然后将顶点乘以。通常你也有一个模型和一个视图矩阵（或一个组合的模型视图矩阵，就像在OpenGL ES 1中一样），你可以在投影变换之前转换你的顶点：

The glOrtho method does nothing else than create a new matrix and multiply the current projection matrix by this matrix. With OpenGL ES 2.0 you have to manage matrices yourself. In order to replicate the glOrtho behaviour you need a uniform for the projection matrix in your vertex shader, which you then multiply your vertices with. Usually you also have a model and a view matrix (or a combined modelview matrix, like in OpenGL ES 1) which you transform your vertices with before the projection transform:

uniform mat4 projection;
uniform mat4 modelview;

attribute vec4 vertex;

void main()
{
    gl_Position = projection * (modelview * vertex);
}

glOrtho 此处找到$ c>构造。

The specific projection matrix that glOrtho constructs can be found here.

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