Playing around with Processing, I came to a situation where I want to draw text on top of 3D objects being transformed:
pushMatrix();
noFill();
stroke(c, 128);
translate(width/2, height/2);
// misc. 3D drawing code goes here. Finally draw text:
fill(255);
textAlign(CENTER, CENTER);
text("...ןעוט", width/2, height/2);
The resulting image has a depth problem. Anything behind the text appears to be black for no good reason. See image below:
I don't want this to happen. I want the text to be see-through where it needs to be. How would I solve this?
I'm afraid I can't explain exactly why and how but what I did was add:
textMode(SHAPE);
Which solved the issue. Somehow.
Related
I want to create an app in Cocos2d/Cocos2dx in which i have an image which is not visible but when i move my finger on device it start drawing. Only that part of image draws where i move my finger.
Thanks in Advance
There are two ways I can think of drawing an image.
The first way would be like a brush. You would use RenderTexture and draw/visit a brush sprite to draw it into this texture. If you just need to draw with solid colors (can have opacity) you could also use the primitive draw commands (drawCircle, drawPoly, drawSegment). You will need a high rate of touch tracking and will likely want to draw segments or bezier curves between touch movements to catch fast movements.
http://discuss.cocos2d-x.org/t/using-rendertexture-to-render-one-sprite-multiple-times/16332/3
http://discuss.cocos2d-x.org/t/freehand-drawing-app-with-cocos2d-x-v3-3-using-rendertexture/17567/9
Searching on how other drawing games work would be useful.
The second way I can envision it is similar to revealing except using an inverse mask. So you would draw a set image, but reveal that image by drawing.
http://www.raywenderlich.com/4428/how-to-mask-a-sprite-with-cocos2d-2-0
There are more elaborate ways to handle the drawing into the RenderTexture in order to have the brush design tile correctly and repeat based on a given size, but that'll involve making something closer to an image editing tool.
I'm creating a box and placing "magnets" on the bottom. The sides are slightly see through(alpha is somewhere between .2 and .5) and the bottom is solid. I'm trying to use gluUnProject() to select where the "magnet" is placed, but when the sides of the box are rendered, I can't get my magnets into the box.
Is there anyway to still have the sides of the wall to be rendered but ignore them for the sake of mouse clicks?
I've tried GL_CULL_FACE but at first glance that doesn't seem to be what I'm looking for.
So if I understand correctly, you have semi-transparent boxes and when the magnet is inside the boxes you want to see the magnet in according to the semi-transparency of the boxes.
My guess is that when you're drawing the boxes you have the depth writes turned on, this way if boxes happen to get drawn before the magnet, then when you draw the magnet it will fail the depth test and the part that's inside won't get drawn as a result.
The easiest way to do this is:
Draw all the solid objects first
Disable depth writes:
glDepthMask(GL_FALSE);
Use an order-independent blending function when drawing the semi-transparent objects, for example:
glBlendFunc(GL_ONE, GL_ONE)
Draw all your transparent objects
Enable depth writes again
glDepthMask(GL_TRUE);
Bear in mind this simple method will only work if you can get away with using an commutative blending equation, if not then consider using order-independent transparency, a good article is "Efficient Layered Fragment Buffer Techniques" By Pyarelal Knowles, Geoff Leach, and Fabio Zambetta
I'm making a 2D game that uses directx. Currently, I have a background texture (with more to come) that I draw to the screen. However, I only want a portion of the texture drawn to the screen. I know that I could use a rectangle with the draw function, but I need a greater degree of control. Is there a way to draw several triangles (using custom vertices) to the screen from my drawing? I've looked around the internet and this site, but I just can't seem to find what I want. I can give more information/code if needed. Thank you!
When you draw a line in OpenGL, glLineWidth creates a fixed-size line, regardless how close the line is to you.
I wanted to draw a line that will appear bigger when it's close. Now, I understand that if I use a rectangle to achieve this effect, it will look a bit pixelated once the polygon is far enough.
What I've previously done is to draw a normal GL_LINE up to the point where the line would get bigger than the pixel size, and then continue with a rectangle from that point. However, it's not as fast as just chucking everything down to a vertex array or VBO, as it had to be recalculated every frame.
What other methods are available? Or am I stuck with this?
I like to use a gradated texture like this to draw lines:
This is really the alpha of my texture. So you have a fully opaque center fading to fully transparent at the edges. Then you can draw your line using a rectangle with points:
(x1,y1,0,0), (x2,y1,1,0), (x1,y2,0,1), (x2,y2,1,1)
where the last two entries in each tuple are u and v of the texture. It ends up looking very smooth. You can even string together lots of very small rectangles to make curvy lines.
If you're just drawing a bunch of lines and want a quick and easy depth effect try adding fog. The attenuation of the lines as they recede makes our brains think they're 3d. This isn't going to work if the near ends are really close to the viewer.
If you want your lines be thicker on near end and thinner on far end, I suppose you have to model them from polygons.
I am currently using glLogicOp() with a cube, which i render twice: with glFrontFace(GL_CW) and then with glFrontFace(GL_CCW). This allows me to see which area of the other 3d object my cube is overlapping with.
But i want to change the negative color to something else, lets say 0.5f transparent blue color.
How this can be done? Sorry about the title, i dont know the name of this method.
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Also, i am having problem with being inside the cube with my camera: i need to fill the screen with negative coloring, is there any other way than swithing to 2d mode and drawing a quad with glLogicOp() enabled ? Also the problem is that theres a chance to see bugged rendering if i am at the edge of the cube surface, any ideas for preventing this perfectly?
You should look into the "Carmack's reverse" algorithm and the stencil shadow algorithms in general, as your problem is closely related to them (your cube being a shadow volume object). You will not get away with using glLogicOp() if you want other colors than black and white.