unity - blender transparent texture white




Blending transparent textures with depth (3)

Enabling depth test doesn’t actually sort your geometry by depth—in the usual GL_LESS case, it merely prevents primitives from drawing if they aren’t closer to the viewer than what has previously been drawn. This allows you to draw opaque geometry in whatever order you want and still get the desired result, but correct rendering of blended geometry typically requires everything behind the blended object to have already been rendered.

Here’s what you should be doing to get a mix of opaque and blended geometry to look right:

  1. Separate your blended geometry from your opaque geometry.
  2. Sort your blended geometry from back to front.
  3. Draw all the opaque geometry first as usual.
  4. Draw your blended geometry in sorted order. You’ll want to leave depth testing enabled but temporarily disable depth writes with glDepthMask(GL_FALSE).

Alternately, if your content is always either fully opaque or fully transparent, you can just enable alpha testing and disable blending, but I’m guessing that’s not what you’re looking for.

I am trying to blend textures which have transparent areas:

glEnable( GL_TEXTURE_2D );
glBindTexture( GL_TEXTURE_2D, ...);
glVertexPointer( 2, GL_FLOAT, 0, ... );
glEnable (GL_BLEND);
glBlendFunc (GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
glDrawArrays( GL_TRIANGLE_STRIP, 0, 4 );

Unless I add glDisable(GL_DEPTH_TEST), transparent parts of the top textures overwrite everything beneath them (instead of blending). Is there any way to do this without disabling depth? I have tried various blending functions but none of the helped.


If you're in WebGL or OpenGL ES 2.0 (iPhone/Android) there is no alpha testing. Instead you need to not draw transparent pixels. That way they won't affect the depth buffer since no pixel was written. To do that you need to discard pixels that are transparent in your fragment shader. You could hard code it

...
void main() {
   vec4 color = texture2D(u_someSampler, v_someUVs);
   if (color.a == 0.0) {
     discard;
   }
   gl_FragColor = color;
}

or you could simulate the old style alpha testing where you can set the alpha value

...
uniform float u_alphaTest;
void main() {
   vec4 color = texture2D(u_someSampler, v_someUVs);
   if (color.a < u_alphaTest) {
     discard;
   }
   gl_FragColor = color;
}

Rendering glitch with GL_DEPTH_TEST and transparent textures

That link (and sorting on CPU) is for alpha blending. If you need only Alpha Testing (not Blending), then you don't need to sort anything. Just enable alpha test, keeping depth test enabled, and everything will be rendered fine.

See here: http://www.opengl.org/wiki/Transparency_Sorting You need "Alpha test" that requires alpha testing, not "Standard translucent" that requires sorting.