移植Gfx_SetTransform函数

Question

首先，我是图形编程微笑的核心。

我支持基于HGE移植版本的游戏，它不包含Gfx_SetTransform.的OpenGL版本我发现了几个例子的HGE-Opengl移植，但任何一个例子都有这个功能.

代码：

void CALL HGE_Impl::Gfx_SetTransform(float x, float y, float dx, float dy, float rot, float hscale, float vscale)
{
   D3DXMATRIX tmp;

   if(vscale==0.0f) D3DXMatrixIdentity(&matView);
   else
   {
      D3DXMatrixTranslation(&matView, -x, -y, 0.0f);
      D3DXMatrixScaling(&tmp, hscale, vscale, 1.0f);
      D3DXMatrixMultiply(&matView, &matView, &tmp);
      D3DXMatrixRotationZ(&tmp, -rot);
      D3DXMatrixMultiply(&matView, &matView, &tmp);
      D3DXMatrixTranslation(&tmp, x+dx, y+dy, 0.0f);
      D3DXMatrixMultiply(&matView, &matView, &tmp);
   }

   _render_batch();
   pD3DDevice->SetTransform(D3DTS_VIEW, &matView);
}

那么，有谁能帮助移植Gfx_SetTransform或者提出建议(可能是一些简单的示例或OpenGL函数，我应该去寻找)？谢谢。

Answer 1

如果OpenGL的版本不包括3，您可以用以下方法替换它：

void GL2_SetTransform(float x, float y, float dx, float dy, float rot, float hscale, float vscale)
{
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity(); // we start off a identity matrix

   // Instead of testing for 0, you should test for some
   // threshold, to increase numerical stability
   if( fabs(vscale) >= 1e-7 ) {
      glTranslatef(-x, -y, 0.0f);
      glScalef(hscale, vscale, 1.0f);
      glRotatef(-rot, 0., 0., 1.);
      glTranslatef(x+dx, y+dy, 0.0f);
   }
}

OpenGL-3不推荐使用矩阵操作函数，因此代码看起来与DirectX版本几乎相同(为了提高稳定性，我做了一些更改)：

typedef float mat4x4[4][4];
// OpenGL uses column major mode, so the first
// index selects column, the second row - this is
// opposite to the usual C notation.

// The following functions must be implemented as well.
// But they're easy enough.

// function to set the matrix to identity
void mat4x4_identity(mat4x4 *M);

// those functions transform the matrix in-place,
// i.e. no temporaries needed.
void mat4x4_rotX(mat4x4 *M, float angle);
void mat4x4_rotY(mat4x4 *M, float angle);
void mat4x4_rotZ(mat4x4 *M, float angle);

void mat4x4_scale(mat4x4 *M, float x, float y, float z);

void mat4x4_translate(mat4x4 *M, float x, float y, float z);


void GL3_SetTransform(float x, float y, float dx, float dy, float rot, float hscale, float vscale)
{
   mat4x4 view;
   mat4x4_identity(view);

   if( fabs(vscale) >= 1e-8 ) {
      mat4x4_translate(view, -x, -y, 0.0f);
      mat4x4_scale(view, hscale, vscale, 1.0f);
      mat4x4_rotZ(view, -rot);
      mat4x4_translate(view, x+dx, y+dy, 0.0f);
   }

   _render_batch();
   // get_view_uniform_location returns the handle for the currently loaded
   // shader's modelview matrix' location. Application specific, so you've to
   // come up with that yourself.
   glUniformMatrix4fv(get_view_uniform_locaton(), 1, false, view);
}

我在这里为矩阵操作函数提供了源代码：http://pastebin.com/R0PHTW0M --它们使用的命名方案并不完全相同。