our live wallpaper doesn't work properly on Motorola Atrix phone. It has a stock ROM w/ Android 2.3.
It looks like discard command of fragment shader doesn't work resulting image without transparent parts.
The problem doesn't appear on Desire S w/ Android 2.3, Mototola Droid w/ CM9, ASUS Transformer w/ 4.0, Samsung Galaxy Note w/ 4.0. So the problem seems to be very specific to Motorola Atrix phone.
We use ETC1 compressed textures so alpha channel is passed to shader via separate texture sampler - sTexture is used for main diffuse texture and sAlpha has black-and-white alpha channel.
Here is code for fragment and vertex shaders:
private final String mVertexShader = "uniform highp mat4 uMVPMatrix;\n" +
"attribute highp vec4 aPosition;\n" +
"attribute highp vec2 aTextureCoord;\n" +
"varying mediump vec2 vTextureCoord;\n" +
"void main() {\n" +
" gl_Position = uMVPMatrix * aPosition;\n" +
" vTextureCoord = aTextureCoord;\n" +
"}\n";
private final String mAlphaFragmentShader = "precision mediump float;\n" +
"varying mediump vec2 vTextureCoord;\n" +
"uniform sampler2D sTexture;\n" +
"uniform sampler2D sAlpha;\n" +
"void main() {\n" +
" vec4 base = texture2D(sTexture, vTextureCoord);\n" +
" gl_FragColor = base;\n" +
" if(texture2D(sAlpha, vTextureCoord).r < 0.5){ discard; }\n" +
"}";
OK so I've fixed this. Many thanks to #Tim for willing to run test apps on device and providing me screenshots.
I've modified fragment shader the following way:
private final String mAlphaFragmentShader = "precision mediump float;\n" +
"varying mediump vec2 vTextureCoord;\n" +
"uniform sampler2D sTexture;\n" +
"uniform sampler2D sAlpha;\n" +
"void main() {\n" +
" vec4 base = texture2D(sTexture, vTextureCoord);\n" +
" vec4 mask = texture2D(sAlpha, vTextureCoord);\n" +
" gl_FragColor = base;\n" +
" if(mask.g < 0.5){ discard; }\n" +
"}";
It seems that Motorola Atrix OpenGL drivers treat compressed textures in wrong way and sample R channel as A channel which is always 1.0 in case of ETC1 compressed textures. It looks like internal format of texture is treated as ARGB instead of RGBA. Since my mask texture is black-and-white I can fetch any other colour. Green works just fine.
Related
I have a Fragment Shader like this:
final String fragmentShader =
"precision mediump float;" +
"uniform sampler2D u_texture;" +
"varying vec2 v_texCoord;" +
"void main() {" +
" lowp vec4 textureColor = texture2D(u_texture, v_texCoord);" +
" gl_FragColor = textureColor;" +
"}";
When drawing in GLSurfaceView, I will bind a texture into u_texture, and draw with texture coordinate v_texCoord.
But now I want to change to replace the texture with solid RGBA color. I use uniform vec4 vColor; to pass 4 floats directly as color.
I know there are a way to do it using:
"gl_FragColor = (vColor * texture2D(u_texture, v_texCoord));"
But as I said above, I don't want to bind sampler2D u_texture any more, I just want to fill it directly with solid color AND FOLLOW the texture coordinate.
I am a freshman with OpenGL. I try to find the solution to my problem. I have recorded a video with alpha mask. The top part of video RGB and bottom is alpha. As I understand need to change my shaders, but I don`t understand how to do this.
Vertex shader
private static final String vertexShaderCode =
"attribute vec4 vPosition;" +
"attribute vec4 vTexCoordinate;" +
"uniform mat4 textureTransform;" +
"varying vec2 v_TexCoordinate;" +
"void main() {" +
" v_TexCoordinate = (textureTransform * vTexCoordinate).xy;" +
" gl_Position = vPosition;" +
"}";
Fragment shader
private static final String fragmentShaderCode =
"#extension GL_OES_EGL_image_external : require\n" +
"precision mediump float;" +
"uniform samplerExternalOES texture;" +
"varying vec2 v_TexCoordinate;" +
"void main () {" +
" vec4 color = texture2D(texture, v_TexCoordinate);" +
" gl_FragColor = color;" +
"}";
To skip fragments you can use the discard keyword in the fragment shader.
You have to do 2 look ups to the texture. The first one in the upper half, to get the RGB color channels and the 2nd one in the lower half to get the mask from the red color channel:
vec2 c_uv = vec2(texture.x, texture.y*0.5);
vec4 color = texture2D(c_uv, v_TexCoordinate);
vec2 m_uv = vec2(texture.x, 0.5 + texture.y*0.5);
float mask = texture2D(m_uv, v_TexCoordinate).r;
The fragment shader may look like this:
#extension GL_OES_EGL_image_external : require
precision mediump float;
uniform samplerExternalOES texture;
varying vec2 v_TexCoordinate;
void main () {
vec2 m_uv = vec2(v_TexCoordinate.x, 0.5 + v_TexCoordinate.y*0.5);
float mask = texture2D(texture, m_uv).r;
if ( mask < 0.5 )
discard;
vec2 c_uv = vec2(v_TexCoordinate.x, v_TexCoordinate.y*0.5);
vec4 color = texture2D(texture, c_uv);
gl_FragColor = color;
}
My Android program must use glBlitFrameBuffer() function to copy FrameBuffer object. But glBlitFrameBuffer() function is only supported on OpenGL ES 3.0+ devices. I want to support OpenGL ES 2.0+ devices.
Is there any solution/alternative for this function?
Bind texture that used as collor attachment on source frame buffer
Bind destination framebuffer
Draw full screen quad (if you need stretch or offseted reading manipulate with vertex/tex coordinates)
Fetch data from bound texture in frament shader and put it to gl_FragColor
I've created a CopyShader that simply uses a shader to copy from a texture to a framebuffer.
private static final String SHADER_VERTEX = ""
+ "attribute vec4 a_Position;\n"
+ "varying highp vec2 v_TexCoordinate;\n"
+ "void main() {\n"
+ " v_TexCoordinate = a_Position.xy * 0.5 + 0.5;\n"
+ " gl_Position = a_Position;\n"
+ "}\n";
private static final String SHADER_FRAGMENT = ""
+ ""
+ "uniform sampler2D u_Texture;\n"
+ "varying highp vec2 v_TexCoordinate;\n"
+ "void main() {\n"
+ " gl_FragColor = texture2D(u_Texture, v_TexCoordinate);\n"
+ "}\n”;
Use these as your shaders, and then just set u_Texture to the texture you want to copy from, and bind the framebuffer you want to write to, and you should be set.
I have an android app in which I use openGL to make some neat image effects.
The base setup is that I continually draw the buffer to one of two textures, then draw on top of that texture the next frame (essentially a simulation), to give the effect that the same image keeps getting manipulated.
I'm trying to add a fade effect to this, in which I darken the background, then draw on top of that, but I'm getting a very strange artifact from this. Here is my fragment shader:
private final String mCompositeFragmentShader =
"#extension GL_OES_EGL_image_external : require\n" +
"precision mediump float;\n" +
"varying vec2 bTextureCoord;\n" +
"varying vec2 vTextureCoord;\n" +
"uniform samplerExternalOES sTexture;\n" +
"uniform sampler2D bufferTexture;\n" +
"uniform float gamma; \n" +
"void main() {\n" +
" vec4 camera = texture2D(sTexture, vTextureCoord);\n" +
" camera.r = pow(camera.r, 1.0/gamma);\n" +
" camera.g = pow(camera.g, 1.0/gamma);\n" +
" camera.b = pow(camera.b, 1.0/gamma);\n" +
" vec4 bg = texture2D(bufferTexture, bTextureCoord);\n" +
" vec3 color = max(camera.rgb, bg.rgb -vec3(.02, .02, .02));\n"+
" gl_FragColor = vec4(color,1.0);\n" +
"}\n";
with the relevant bit of code being:
vec3 color = max(camera.rgb, bg.rgb -vec3(.02, .02, .02));
So I would expect light areas to eventually fade to black over time. However, instead of black it's fading to a magenta grid:
You can see that the gridding is different for each triangle being drawn on the screen (I'm only drawing two triangles).
Here is the vertex shader, just in case:
"uniform mat4 uMVPMatrix;\n" +
"uniform mat4 uSTMatrix;\n" +
"attribute vec4 aPosition;\n" +
"attribute vec4 aTextureCoord;\n" +
"varying vec4 tempCoords;" +
"varying vec2 vTextureCoord;\n" +
"varying vec2 bTextureCoord;\n" +
"void main() {\n" +
" gl_Position = aPosition;\n" +
" bTextureCoord = aTextureCoord.xy;\n" +
" tempCoords = aTextureCoord;\n" +
" tempCoords.y = aTextureCoord.y * ("+previewSize.height+".0 /"+previewSize.width+".0);\n" +
" vTextureCoord = (uSTMatrix * tempCoords).xy;\n" +
"}\n";
Anyone have any idea what's causing this, and how to fix it?
This vertex shader code works on every device except for the Galaxy Note 2.
gl_Position = uMVPMatrix * vPosition;
where if I reverse the matrix multiplication to:
gl_Position = vPosition * uMVPMatrix; I can actually get things to appear.
Unfortunately, the reverse would require me to completely rewrite my transformations library.
Does anyone have any insight on what could be causing this, is this an opengl driver error with the device?
Shader code
private final String vertexShaderCode =
// This matrix member variable provides a hook to manipulate
// the coordinates of the objects that use this vertex shader
"uniform mat4 uMVPMatrix;" +
"attribute vec4 vPosition;" +
"attribute vec2 a_TexCoordinate;" +
"varying vec2 v_TexCoordinate;" +
"void main() {" +
// the matrix must be included as a modifier of gl_Position
"v_TexCoordinate = a_TexCoordinate;" +
"gl_Position = uMVPMatrix * vPosition;" +
"}";
private final String fragmentShaderCode =
"precision mediump float;" +
"uniform sampler2D u_Texture;" +
"varying vec2 v_TexCoordinate;" +
"void main() {" +
" gl_FragColor = texture2D(u_Texture, v_TexCoordinate);" +
//" gl_FragColor = vec4(v_TexCoordinate, 0, 1);" +
"}";
This is not about only a galaxy note 2 platform.
This is a mathematical question. Because both glsl/hlsl uses column major order,
It is a right way to multiply MATRIX x VECTOR
or
you can transpose the matrix using a option in
glUniformMatrix4fv( h_Uniforms[UNIFORMS_PROJECTION], 1, GL_FALSE or GL_TRUE, g_proxtrans.s);
Apparently, It can be a problem not to call this function with the option ( GL_TRUE is to use transposing ) each every frame just try .