c++ - 使用 glPointSize 的像素宽度 - 无效

Question

我有这个丢分代码。我想增加点数。现在我使用此命令 glPointSize 但没有任何反应。磅值是默认值。它不会增加。
我怎样才能增加点数？

glBegin(GL_POINTS);

glColor3f (a, b, c);
glPointSize(20.0f); 

glVertex2i(px, py);
glEnd();

Answer 1

glPointSize(20.0f); 必须放在glBegin() 之前，否则不会有任何效果。这样做:

glPointSize(20.0f); 

glBegin(GL_POINTS);
   glColor3f (a, b, c);
   glVertex2i(px, py);
glEnd();

在 OpenGL 中 documentation ，你可以读到:

Only a subset of GL commands can be used between glBegin and glEnd. The commands are glVertex, glColor, glIndex, glNormal, glTexCoord, glEvalCoord, glEvalPoint, glArrayElement, glMaterial, and glEdgeFlag. Also, it is acceptable to use glCallList or glCallLists to execute display lists that include only the preceding commands. If any other GL command is executed between glBegin and glEnd, the error flag is set and the command is ignored.