的Open GL ES線路沒有終點

Question

我用下面的代碼行畫從點A線到B點

const GLfloat line[] = { 
    0.0f, 0.0f, //point A 
    2.5f, -1.0f, //point B 
}; 
glColor4f(0.0f,1.0f,0.0f,1.0f); 
glVertexPointer(2, GL_FLOAT, 0, line); 
glEnableClientState(GL_VERTEX_ARRAY); 
glDrawArrays(GL_LINES, 0, 2);  

但我的問題是線路在沒有結束點B，它通過點B並繼續繪製。所以我得到一條沒有終點的線。任何形式的幫助表示讚賞。 謝謝。

這是我整個功能的樣子。

- （無效）popupCircles {

[EAGLContext setCurrentContext:context]; 
glBindFramebufferOES(GL_FRAMEBUFFER_OES, viewFramebuffer); 
glViewport(0, 0, backingWidth, backingHeight); 
glMatrixMode(GL_PROJECTION); 
glLoadIdentity(); 
glOrthof(-1.0f, 1.0f, -1.5f, 1.5f, -1.0f, 1.0f); 
glMatrixMode(GL_MODELVIEW); 
glClearColor(0.0f, 0.0f, 0.0f, 1.0f); 
glClear(GL_COLOR_BUFFER_BIT); 
glPushMatrix(); 
const GLfloat line[] = { 
    0.0f, 0.0f, //point A 
    2.5f, -1.0f, //point B 
}; 
glColor4f(0.0f,1.0f,0.0f,1.0f); //line color 
glVertexPointer(2, GL_FLOAT, 0, line); 
glEnableClientState(GL_VERTEX_ARRAY); 
glDrawArrays(GL_LINES, 0, 2);  
glPopMatrix();  

glPushMatrix(); 
const GLfloat line2[] = { 
    0.0f, 0.0f, //point A 
    -2.5f, -1.0f, //point B 
}; 
glColor4f(0.0f,1.0f,0.0f,1.0f); //line color 
glVertexPointer(2, GL_FLOAT, 0, line2); 
glEnableClientState(GL_VERTEX_ARRAY); 
glDrawArrays(GL_LINES, 0, 2);  
glPopMatrix(); 

glPushMatrix(); 
const GLfloat line3[] = { 
    0.0f, 0.0f, //point A 
    1.0f, 3.0f, //point B 
}; 
glColor4f(0.0f,1.0f,0.0f,1.0f); //line color 
glVertexPointer(2, GL_FLOAT, 0, line3); 
glEnableClientState(GL_VERTEX_ARRAY); 
glDrawArrays(GL_LINES, 0, 2);  
glPopMatrix();  
glVertexPointer(2, GL_FLOAT, 0, square); 
glEnableClientState(GL_VERTEX_ARRAY); 
glColor4f(1.0f, 0.0f, 0.0f, 1.0f); 
glPushMatrix(); 
glScalef(trans, trans, trans); 
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); 
glPopMatrix();  
glPushMatrix(); 
glScalef(trans, trans, trans); 
glTranslatef(2.5f, -1.0f, 0.0f); 
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); 
glPopMatrix(); 
glPushMatrix(); 
glScalef(trans, trans, trans); 
glTranslatef(-2.5f, -1.0f, 0.0f); 
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); 
glPopMatrix(); 
glPushMatrix(); 
glScalef(trans, trans, trans); 
glTranslatef(1.0f, 3.0f, 0.0f); 
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); 
glPopMatrix(); 
glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer); 
[context presentRenderbuffer:GL_RENDERBUFFER_OES]; 

}

Answer 1

如果尚未指定的投影和模型視圖矩陣，那麼B點是視，它是在範圍[外 - 1，1]的x和y維度。

編輯（響應於經修正的問題）：點B是通過調用glOrthof()設定的邊界之外，所以線應該熄滅視口的邊緣。