Android Opengl 2.0 Alpha Blending Problem - Half Transparent Textures

Question

I have this problem with Apha Blending in my game, when I draw a surface with an alpha texture, what is destined to be invisible is invisible, but the parts that are supposedly visible are half transparent. It depends on the amount of light - the closer it is to the light source, the better it looks, but in the shadow such objects almost disappear.

I turn on Alpha Blending:

GLES20.glEnable(GLES20.GL_BLEND); 

then I set the function:

 GLES20.glBlendFunc(GLES20.GL_SRC_ALPHA, GLES20.GL_ONE_MINUS_SRC_ALPHA); 

or

 GLES20.glBlendFunc(GLES20.GL_ONE, GLES20.GL_ONE_MINUS_SRC_ALPHA); 

Effect

all the same. I am using 48 bit PNG files with alpha channel.

my fragment shader is as follows:

 final String fragmentShader = "precision mediump float; \n" +"uniform vec3 u_LightPos; \n" +"uniform sampler2D u_Texture; \n" +"varying vec3 v_Position; \n" +"varying vec4 v_Color; \n" +"varying vec3 v_Normal; \n" +"varying vec2 v_TexCoordinate; \n" +"void main() \n" +"{ \n" +"float distance = length(u_LightPos - v_Position); \n" +"vec3 lightVector = normalize(u_LightPos - v_Position); \n" +"float diffuse = max(dot(v_Normal, lightVector), 0.0); \n" +"diffuse = diffuse * (" + Float.toString((float)Brightness) +" / (1.0 + (0.08 * distance))); \n" +"diffuse = diffuse; \n" //+3 +"gl_FragColor = (v_Color * diffuse * texture2D(u_Texture, v_TexCoordinate)); \n" +"} \n"; 

and vertex shader:

 uniform mat4 u_MVPMatrix; uniform mat4 u_MVMatrix; attribute vec4 a_Position; attribute vec3 a_Normal; attribute vec2 a_TexCoordinate; varying vec3 v_Position; varying vec4 v_Color; varying vec3 v_Normal; varying vec2 v_TexCoordinate; void main() { v_Position = vec3(u_MVMatrix * a_Position); v_Color = a_Color; v_TexCoordinate = a_TexCoordinate; v_Normal = vec3(u_MVMatrix * vec4(a_Normal, 0.0)); gl_Position = u_MVPMatrix * a_Position; } Thx for any suggestions:) 

Answer 1

Your fragment shader multiplies all 4 (RGBA) texture color components with a diffusion coefficient. This will cause your alpha component to go to zero whenever the scattered light disappears, making your sprites invisible.

To fix your code, change it to something like this:

 gl_FragColor = v_Color * texture2D(u_Texture, v_TexCoordinate); gl_FragColor.rgb *= diffuse;