I am beginning to learn OpenGL ES 1.1 for iPhone and would like to draw a 2D image in orthographic projection behind a few 3D objects. Using Jeff Lamarche’s tutorials and the book Pro OpenGL ES for iPhone and I’ve come up with the following couple methods to attempt to do this. If I disable the call to drawSunInRect the 3D objects are rendered just fine and I can move them with touch controls etc. If I uncomment that call and try to draw the sun image, the image appears in the CGRect I supply, but I cannot see any of my other 3D objects – the rest of the screen is black. I’ve tried to disable/enable depth testing in various places, pass different parameters to glOrthof(), and move around the rectangle but I keep getting the sun image only when the drawSunInRect method is called. I’m assuming it is covering my 3D objects.
// 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];
}
UPDATE
I modified the draw sun method to have only 1 push and 1 pop for the GL_PROJECTION. I am still having the same issue. The sun image appears but I cannot see my 3D Objects. I have tried to re-arrange the calls to the render methods so the 3D objects are rendered first but I get the same results. I would appreciate other ideas on how to see my orthographic texture and 3D objects together.
// 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);
I realized I was calling setClipping only once in my viewController viewDidLoad. I moved it to my glkView method and now I get my Sun image and my 3d object.