應該是3色的黃色三角OpenGL

這可能是一個愚蠢的錯誤，但我不能看到它？！我有定義幾何和類的渲染幾何的類。現在它是每個頂點的基本三角形和顏色。應該是3色的黃色三角OpenGL

這裏是代碼定義所述幾何對象的數據：

CGeometry* g = new CGeometry(); 
g->vertexes = new double[3*3]; 

g->vertexes[0] = 0; 
g->vertexes[1] = 0; 
g->vertexes[2] = 0; 

g->vertexes[3] = 100; 
g->vertexes[4] = 100; 
g->vertexes[5] = 0; 

g->vertexes[6] = 100; 
g->vertexes[7] = 0; 
g->vertexes[8] = 0; 

g->colors = new double[12]; 

g->colors[0] = 1; 
g->colors[1] = 1; 
g->colors[2] = 0; 
g->colors[3] = 1; 

g->colors[4] = 1; 
g->colors[5] = 0; 
g->colors[6] = 1; 
g->colors[7] = 0; 

g->colors[8] = 0; 
g->colors[9] = 1; 
g->colors[10] = 1; 
g->colors[11] = 0;

這裏是呈現上述數據代碼：

CGeometry* g = object->geometry; 

int j = object->endIndex - object->startIndex; 
double* vertexes = g->vertexes; 
double* colors = g->colors; 

glBegin(GL_TRIANGLES); 
{ 
    for(int i = 0; i < j; i++){ 
     int coord = object->startIndex+i; 
     int colorind = coord*4; 

     double r,g,b,a; 
     r = colors[colorind]; 
     g = colors[colorind+1]; 
     b = colors[colorind+2]; 
     a = colors[colorind+3]; 

     glColor4d( r,g,b,a); 
     glVertex3d(vertexes[coord*3], 
        vertexes[coord*3+1], 
        vertexes[coord*3+2]); 
    } 
} 
glEnd();

然而，不管是什麼，我把我的三角形始終是黃色的，或顏色數組中第一種顏色的值。我已經進入調試器並檢查每個單獨循環迭代的值，並且r g b和一個變量的值實際上相應地改變，並且不總是黃色，但結果是黃色三角形。

然而，如果我把下面從neheGL教程抓獲：

glClearColor(0.1f,0.1f,0.1f,1); 
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer 
glLoadIdentity();         // Reset The Current Modelview Matrix 
//glTranslatef(1.5f,0.0f,0.0f);      // Move Left 1.5 Units And Into The Screen 6.0 
glBegin(GL_TRIANGLES);        // Drawing Using Triangles 
    glColor3f(1.0f,0.0f,0.0f);      // Set The Color To Red 
    glVertex3f(0.0f, 1.0f, 0.0f);     // Top 
    glColor3f(0.0f,1.0f,0.0f);      // Set The Color To Green 
    glVertex3f(-1.0f,-1.0f, 0.0f);     // Bottom Left 
    glColor3f(0.0f,0.0f,1.0f);      // Set The Color To Blue 
    glVertex3f(1.0f,-1.0f, 0.0f);     // Bottom Right 
glEnd();           // Finished Drawing The Triangle 
glTranslatef(160.0f,0.0f,0.0f);      // Move Right 3 Units 
glColor3f(0.5f,0.5f,1.0f);       // Set The Color To Blue One Time Only 
glBegin(GL_QUADS);         // Draw A Quad 
    glVertex3f(-1.0f, 1.0f, 0.0f);     // Top Left 
    glVertex3f(1.0f, 1.0f, 0.0f);     // Top Right 
    glVertex3f(1.0f,-1.0f, 0.0f);     // Bottom Right 
    glVertex3f(-1.0f,-1.0f, 0.0f);     // Bottom Left 
glEnd();

我得到3種顏色一個很好的混合三角形的每個頂點

來源

2009-02-16 Tom J Nowell