I'm trying to render a set of textured geometry to a single FBO, and then render that FBO to the scene. The problem is that overlapping semi-transparent areas of that geometry are not rendered correctly. They end up too opaque and dark.
If I render the geometry directly to the scene it renders correctly, but I need to render it first to the FBO.
By the way, I'm using the following for blending (according to opengl - blending with previous contents of framebuffer):
rendering geometry to the FBO: glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE)
rendering the FBO to the scene: glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA)
I'm doing this for OpenGL ES 2.0.
Actually, I found that the problem was the blending function used to render the geometry to the FBO.
Instead of:
glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE)
I have to use:
glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA)
And now it works as good as if I was rendering the geometry directly to the scene.
Related
I have a texture and I want to draw it to a FrameBufferObject. The texture has transparent areas. I would like the following:
For all transparent pixels, let them be drawn transparent in the FrameBufferObject.
For all non-transparent pixels, let them be drawn using a color of my choosing, ie pure red (ignore their actual rgb value)
I've tried Batch.setColor(red) before drawing the texture, but that just tints it - I want all non-transparent pixels to be drawn pure red.
I am also trying to figure out how to achieve this in just opengl directly, looks like there may be a way to do this with blending, which can then be related back to gdx.
Thanks
You need to write a shader and the shader is the OpenGL program that renders the texture. So your shader would render transparency without change and all else would the color of your own choosing.
The following link has libgdx shaders for palette swapping i.e. direct reassignment of color at render, which you can easily adapt for single color and transparency.
https://www.javaer101.com/en/article/12241616.html
I have some scene in three.js with static objects like solid cubes and so on.
Over this objects I have place some quads each of them is textured with letter image.
When I activate fxaa postprocessing main objects looks fine but letters textures looks not good - blurry and dirty. I think it's because letter texture already antialiased. I can't generate another type of textures because Chrome render font already antialiased and I just get screenshot for texture.
Is it possible somehow exclude some objects from fxaa pass? Maybe make more render passes? Any ideas or samples?
Thanks.
I need to blur render but not whole, only fragments. Frozen "glass" shapes will flowed over (SVG animated transparent shapes over WebGl animation). The problem is local frozen effect. Whether is some effect composer or context.readPixels + FastBlur.js makes sense or maybe css + masks ? Thank you for help.
I did it:
WebGl shader blur (Three.js render passes) + mask texture (image = additional invisible canvas element where shapes are drawn). SVG is an independent element, but gives information about kind of shapes and positions for mask texture and displays shapes of course. A bit crazy but works and very fast.
How do I create a three.js material/geometry which uses part of a texture?
I am first rendering a scene to a texture. This texture is used for a Mesh with a CubeGeometry and a MeshLambertMaterial. What I would like to do now is have only a part of the texture displayed on the cube face (like a window into the texture).
I've done this before using OpenGL ES directly, with shaders, but I don't see what parameters might make it possible using the standard three.js library.
That is what texture coordinates are for. See this question and answer:
http://stackoverflow.com/questions/19366991/drawing-part-of-open-gl-texture/19367844#19367844
Is it possible to render to FBO texture once and then use the resulting texture handle to render all following frames?
For example, in case I'm rendering a hard shadow map and the scene geometry and light position are static, the depth map is always the same and I want to render it only once using a FBO and then just use it after that. However, if I simply put a flag to render the depth texture once, the texture remains empty for the rest of the frames.
Is FBO get reallocated after rendering a frame has been complete? What would be the right way to preserve rendered texture for rendering of the following frames?
Rendering to a texture is no different than if you had uploaded those pixels to the texture in the first place. The contents of a texture do not magically disappear. A texture's contents are changed when you change them. This could be by uploading data to the texture, or by setting one of the texture's images to be used for framebuffer operations (clearing, rendering to it, etc).
Unless you do something to explicitly change the data stored in a texture, it won't change.