我开始学习适用于 iPhone 的 OpenGL ES 1.1，并想在几个 3D 对象后面以正交投影绘制 2D 图像。使用 Jeff Lamarche 的教程和用于 iPhone 的 Pro OpenGL ES 一书，我想出了以下几种方法来尝试做到这一点。如果我禁用对drawSunInRect3D 对象的调用，则渲染得很好，我可以使用触摸控件等移动它们。如果我取消注释该调用并尝试绘制太阳图像，图像会出现在CGRect我提供的图像中，但我看不到任何我的其他 3D 对象 - 屏幕的其余部分是黑色的。我试图在不同的地方禁用/启用深度测试，将不同的参数传递给，并在矩形周围移动，但只有在调用该方法glOrthof()时我才会继续获取太阳图像。drawSunInRect我假设它覆盖了我的 3D 对象。
// Draw Sun in Rect and with Depth
- (void)drawSunInRect:(CGRect)rect withDepth:(float)depth {
// Get screen bounds
CGRect frame = [[UIScreen mainScreen] bounds];
// Calculate vertices from passed CGRect and depth
GLfloat vertices[] =
{
rect.origin.x, rect.origin.y, depth,
rect.origin.x + rect.size.width , rect.origin.y, depth,
rect.origin.x, rect.size.height+rect.origin.y , depth,
rect.origin.x + rect.size.width , rect.size.height+rect.origin.y ,depth
};
// Map the texture coords - no repeating
static GLfloat textureCoords[] =
{
0.0, 0.0,
1.0, 0.0,
0.0, 1.0,
1.0, 1.0
};
// Disable DEPTH test and setup Ortho
glDisable(GL_DEPTH_TEST);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glOrthof(0,frame.size.width,frame.size.height,0,0.1f,1000.0);
// Enable blending and configure
glEnable(GL_BLEND);
glBlendFunc(GL_ONE,GL_ONE_MINUS_SRC_ALPHA);
// Enable VERTEX and TEXTURE client states
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
// Enable Textures
glEnable(GL_TEXTURE_2D);
// Projection Matrix Mode for ortho and reset
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
// No lighting or Depth Mask for 2D - no Culling
glDisable(GL_LIGHTING);
glDepthMask(GL_FALSE);
glDisable(GL_CULL_FACE);
glDisableClientState(GL_COLOR_ARRAY);
// Define ortho
glOrthof(0,frame.size.width,frame.size.height,0,0.1f,1000);
// From Jeff Lamarche Tutorials
// glOrthof(-1.0, // Left
// 1.0, // Right
// -1.0 / (rect.size.width / rect.size.height), // Bottom
// 1.0 / (rect.size.width / rect.size.height), // Top
// 0.01, // Near
// 10000.0); // Far
// Setup Model View Matrix
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
// Bind and draw the Texture
glBindTexture(GL_TEXTURE_2D,sunInt);
glVertexPointer(3, GL_FLOAT, 0, vertices);
glTexCoordPointer(2, GL_FLOAT,0,textureCoords);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glMatrixMode(GL_MODELVIEW);
glPopMatrix();
glMatrixMode(GL_PROJECTION);
glPopMatrix();
// Re-enable lighting
glEnable(GL_LIGHTING);
glDisable(GL_TEXTURE_2D);
glDisable(GL_BLEND);
glDisable(GL_DEPTH_TEST);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDepthMask(GL_TRUE);
}
// Override the draw in rect function
- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect
{
// Initialize and init the rotation stuff for the object
// Identity Matrix
glLoadIdentity();
static GLfloat rot = 0.0;
// Clear any remnants in the drawing buffers
// and fill the background with black
glClearColor(0.0f,0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Render the Sun - 2D Sun Image in CGRect
//[self drawSunInRect:CGRectMake(100, 100, 50, 50) withDepth:-30.0]; // 2D Sun Image
// Render the BattleCruiser - 3D Battlecruiser
[self renderTheBattleCruiser];
// Calculate a time interval to use to rotate the cruiser lives
static NSTimeInterval lastDrawTime;
if (lastDrawTime)
{
NSTimeInterval timeSinceLastDraw = [NSDate timeIntervalSinceReferenceDate] - lastDrawTime;
rot += 75 * timeSinceLastDraw;
}
lastDrawTime = [NSDate timeIntervalSinceReferenceDate];
}
更新
我将 draw sun 方法修改为只有 1 次推送和 1 次弹出GL_PROJECTION。我仍然有同样的问题。太阳图像出现，但我看不到我的 3D 对象。我试图重新安排对渲染方法的调用，以便首先渲染 3D 对象，但我得到了相同的结果。我将不胜感激有关如何同时查看我的正交纹理和 3D 对象的其他想法。
// Draw Sun in Rect and with Depth
- (void)drawSunInRect:(CGRect)rect withDepth:(float)depth {
// Get screen bounds
CGRect frame = [[UIScreen mainScreen] bounds];
// Calculate vertices from passed CGRect and depth
GLfloat vertices[] =
{
rect.origin.x, rect.origin.y, depth,
rect.origin.x + rect.size.width , rect.origin.y, depth,
rect.origin.x, rect.size.height+rect.origin.y , depth,
rect.origin.x + rect.size.width , rect.size.height+rect.origin.y ,depth
};
// Map the texture coords - no repeating
static GLfloat textureCoords[] =
{
0.0, 0.0,
1.0, 0.0,
0.0, 1.0,
1.0, 1.0
};
glEnable(GL_BLEND);
glBlendFunc(GL_ONE,GL_ONE_MINUS_SRC_ALPHA);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glEnable(GL_TEXTURE_2D);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glDisable(GL_LIGHTING);
glEnable(GL_DEPTH_TEST);
glDisable(GL_CULL_FACE);
glDisableClientState(GL_COLOR_ARRAY);
glOrthof(0,frame.size.width,frame.size.height,0,0,1000);
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
glColor4f(1,1,1,1);
glBindTexture(GL_TEXTURE_2D,sunInt);
glVertexPointer(3, GL_FLOAT, 0, vertices);
glTexCoordPointer(2, GL_FLOAT,0,textureCoords);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
glMatrixMode(GL_MODELVIEW);
glPopMatrix();
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glEnable(GL_LIGHTING);
glDisable(GL_TEXTURE_2D);
glDisable(GL_BLEND);
glDisable(GL_DEPTH_TEST);
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);