OpenGL到OpenGL-ES - 改变条带中三角形的颜色

Question

当使用在glBegin()和glEnd()在OpenGL你可以设置和更改每个glVertex3f之间的颜色().如何在使用顶点数组和glDrawArrays()时重新创建此行为.这是常规opengl.

for(angle = 0.0f; angle < (2.0f*GL_PI); angle += (GL_PI/8.0f))
    {
    // Calculate x and y position of the next vertex
    x = 50.0f*sin(angle);
    y = 50.0f*cos(angle);

    // Alternate color between red and green
    if((iPivot %2) == 0)
        glColor3f(0.0f, 1.0f, 0.0f);
    else
        glColor3f(1.0f, 0.0f, 0.0f);

    // Increment pivot to change color next time
    iPivot++;

    // Specify the next vertex for the triangle fan
    glVertex2f(x, y);
    }

Answer 1

使用glDrawArrays,您必须启用glVertexPointer来设置顶点数据.

以同样的方式,您还可以为颜色设置客户端内存指针.

归结为这些调用:

  glEnableClientState (GL_VERTEX_ARRAY);
  glEnableClientState (GL_COLOR_ARRAY); // enables the color-array.

  glVertexPointer (...  // set your vertex-coordinates here..
  glColorPointer (...   // set your color-coorinates here..

  glDrawArrays (... // draw your triangles

顺便说一句 - 纹理坐标以相同的方式处理.只需使用GL_TEXCOORD_ARRAY和glTexCoordPointer即可.