铁汉着色器（OpenGL的ES 2.0） [英] Hud with shaders (opengl-es 2.0)

问题描述

如何画上使用OpenGL ES 2.0的着色器HUD？

How to draw a HUD using shaders on opengl es 2.0?

我有画屏幕上的一个四纹理着色器，它使用MVP矩阵。四有它自己的顶点都是独立的视图位置等（MVP矩阵的原因）

I have a shader which draws a textured quad on screen, it uses MVP matrix. The quad has it own vertices which are independent of view position and so on (cause of MVP matrix)

Matrix.frustumM(mProjMatrix, 0, -ratio, ratio, -1, 1, 3f, 17);
Matrix.setLookAtM(mVMatrix, 0, 0, 0, -5, 0f, 0f, 0f, 0f, 1.0f, 0.0f);

我想显示在右上角（如按钮或别的东西，HUD）相同的四边形。
据我了解，我需要建立一个邻矩阵，而不是frustumM，但我以后应该怎么办？如何顶点着色器应采用四核的顶点？

I'd like to show the same quad on the top right corner (like a button or something else, HUD). As I understand, i need create an ortho matrix instead of "frustumM", but what should i do later? How vertex shader should use vertices of quad?

推荐答案

好吧，你有你的邻矩阵和四，有啥问题，你四的模型视图矩阵转换到所需的位置（X，Y，Z = 0）由邻矩阵相乘，倍增传递矩阵顶点着色器，你的矩阵乘法VERT位置，做:)，我没有使用任何LOOKAT功能在我的code要做到这一点，但我有自己的code为矩阵计算的部分code一些的bada教程，对于投影矩阵我还有其他的功能。

Ok, You have your ortho matrix and quad, so whats the problem, translate modelview matrix of your quad to desired position (x,y,z=0), multiply it by ortho matrix , pass multiplied matrix to vertex shader, multiply vert position by your matrix and done :), i am not using any lookat function in my code to do this, but i have own code for matrices computation its partially code from some bada tutorial, for projection matrix i have other function.

  void
    Letter::Ortho(Matrix* result, float fovy, float aspect, float nearZ, float farZ)
    {
        GLfloat frustumW, frustumH;

        frustumH = tanf(fovy / 360.0f * PI) * nearZ;
        frustumW = frustumH * aspect;

        Frustum(result, -frustumW, frustumW, -frustumH, frustumH, nearZ, farZ);
    }

    void
    Letter::LoadIdentity(Matrix* result)
    {
        memset(result, 0x0, sizeof(Matrix));
        result->m[0][0] = 1.0f;
        result->m[1][1] = 1.0f;
        result->m[2][2] = 1.0f;
        result->m[3][3] = 1.0f;
    }


    void
    Letter::Frustum(Matrix *result, float left, float right, float bottom, float top, float nearZ, float farZ)
    {
        float   deltaX = right - left;
        float   deltaY = top - bottom;
        float   deltaZ = farZ - nearZ;
        Matrix  frustum;

        if ((nearZ <= 0.0f) || (farZ <= 0.0f) ||
            (deltaX <= 0.0f) || (deltaY <= 0.0f) || (deltaZ <= 0.0f))
        {
             return;
        }

        frustum.m[0][0] = 2.0f * nearZ / deltaX;
        frustum.m[0][1] = frustum.m[0][2] = frustum.m[0][3] = 0.0f;

        frustum.m[1][1] = 2.0f * nearZ / deltaY;
        frustum.m[1][0] = frustum.m[1][2] = frustum.m[1][3] = 0.0f;

        frustum.m[2][0] = (right + left) / deltaX;
        frustum.m[2][1] = (top + bottom) / deltaY;
        frustum.m[2][2] = -(nearZ + farZ) / deltaZ;
        frustum.m[2][3] = -1.0f;

        frustum.m[3][2] = -2.0f * nearZ * farZ / deltaZ;
        frustum.m[3][0] = frustum.m[3][1] = frustum.m[3][3] = 0.0f;

        Multiply(result, &frustum, result);
    }

所以，这个code：

So, with this code :

LoadIdentity(&matPerspective);
Ortho(&matPerspective, 60.0f, TEXMANAGER.aspect, -1.0f, 20.0f);
LoadIdentity(&matModelview);
Translate(&matModelview, x ,y ,z);
Scale(&matModelview,size);
//Rotate(&matModelview, 0.0f, 1.0f, 0.0f, 1.0f);
Multiply(&posMatrix, &matModelview, &matPerspective);

和传递posMatrix着色器：）

And pass posMatrix to shader :)

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