OpenGL- Render texture with transapare

Graphics and GPU Programming Programming OpenGL

Started by alireza.pir August 24, 2015 07:15 AM

4 comments, last by alireza.pir 8 years, 8 months ago

246

Author

August 24, 2015 07:15 AM

i have a png image which draw it into my rectangular mesh in opengl, the problem is the image background is transparent but, when i bind it to my mesh, its background gets white; i want the image background to still be transparent.

i tried

glEnableClientState(GLES10.GL_COLOR_ARRAY);

and

glColorPointer

but didn't work as i want.

UPDATE:

the render openGL code:


void render(GL10 gl){


// First allocate texture if there is not one yet.
if (DRAW_TEXTURE && mTextureIds == null) {
// Generate texture.
mTextureIds = new int[2];
gl.glGenTextures(2, mTextureIds, 0);
for (int textureId : mTextureIds) {
// Set texture attributes.
gl.glBindTexture(GL10.GL_TEXTURE_2D, textureId);
gl.glTexParameterf(GL10.GL_TEXTURE_2D,
GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST);
gl.glTexParameterf(GL10.GL_TEXTURE_2D,
GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_NEAREST);
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S,
GL10.GL_CLAMP_TO_EDGE);
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T,
GL10.GL_CLAMP_TO_EDGE);
}
}


if (DRAW_TEXTURE && mPage.getTexturesChanged()) {
gl.glBindTexture(GL10.GL_TEXTURE_2D, mTextureIds[0]);
Bitmap texture = mPage.getTexture(mTextureRectFront,
CurlPage.SIDE_FRONT);
GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, texture, 0);
texture.recycle();


mTextureBack = mPage.hasBackTexture();
if (mTextureBack) {
gl.glBindTexture(GL10.GL_TEXTURE_2D, mTextureIds[1]);
texture = mPage.getTexture(mTextureRectBack,
CurlPage.SIDE_BACK);
GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, texture, 0);
texture.recycle();
} else {
mTextureRectBack.set(mTextureRectFront);
}


mPage.recycle();
reset();
}








// Some 'global' settings.
gl.glEnableClientState(GLES10.GL_VERTEX_ARRAY);


if (DRAW_TEXTURE) {
gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, mBufTexCoords);
}
gl.glVertexPointer(3, GLES10.GL_FLOAT, 0, mBufVertices);
//inja khasiate transparent ro faAl mikonim ke betoonim too CurlPage be kaaghaz alpha bedim
gl.glEnable(GLES10.GL_BLEND);
gl.glBlendFunc(GLES10.GL_SRC_ALPHA, GLES10.GL_ONE_MINUS_SRC_ALPHA);
gl.glDisable(GLES10.GL_LIGHTING);
gl.glDisable(GL10.GL_TEXTURE_2D);


// Draw front texture.
if (DRAW_TEXTURE) {
gl.glEnable(GL10.GL_BLEND);
gl.glEnable(GL10.GL_TEXTURE_2D);


if (!mFlipTexture || !mTextureBack) {
gl.glBindTexture(GL10.GL_TEXTURE_2D, mTextureIds[0]);
} else {
gl.glBindTexture(GL10.GL_TEXTURE_2D, mTextureIds[1]);
}


gl.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);
gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, mVerticesCountFront);


gl.glDisable(GL10.GL_BLEND);
gl.glDisable(GL10.GL_TEXTURE_2D);
}


int backStartIdx = Math.max(0, mVerticesCountFront - 2);
//Log.d("mVerticesCountFront", ""+mVerticesCountFront+"");
int backCount = mVerticesCountFront + mVerticesCountBack - backStartIdx;


// Draw back facing blank vertices.
//gl.glColor4f(1.0f, 0.0f, 0.0f, 0.5f);
gl.glDrawArrays(GLES10.GL_TRIANGLE_STRIP, backStartIdx, backCount);




// Disable textures and color array.
gl.glDisableClientState(GLES10.GL_TEXTURE_COORD_ARRAY);


gl.glDisableClientState(GLES10.GL_VERTEX_ARRAY);
}

OnSurfaceCreated Method:


@Override
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
// mCurlMesh.setup(gl);
gl.glClearColor(0f, 0f, 0f, 0f);
gl.glShadeModel(GL10.GL_SMOOTH);
gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST);
gl.glHint(GL10.GL_LINE_SMOOTH_HINT, GL10.GL_NICEST);
//gl.glHint(GL10.GL_POLYGON_SMOOTH_HINT, GL10.GL_NICEST);
gl.glEnable(GL10.GL_LINE_SMOOTH);
gl.glDisable(GL10.GL_DEPTH_TEST);
gl.glDisable(GL10.GL_CULL_FACE);
gl.glDisable(GL10.GL_DITHER);

}

Waterlimon

4,401

August 24, 2015 09:02 AM

Do you clear the screen before drawing (glClear), does the texture support alpha channel (both the original, and the gl texture you create), if you use custom shader (probably should) does it support the alpha channel (vec4)? Ensure the image loaded in RAM is actually transparent, too (eg print out a pixel in the middle)

o3o

_WeirdCat_

1,512

August 24, 2015 10:12 AM

glColorPointer is used to se vertice colors not texture colors, you do that in shader, (if you set such i thin k you are only able to pass there 4 components per color) i am not sure if es 1.0 supports ffp but if then vertex alpha color is texture alpha? or sth liek that - not worth trying.

either the way you dont load 32 bit texture properly or your shader (if you have one doesnt output the alpha)

Master & Mentor
https://sites.google.com/site/customprog/

alireza.pir

246

Author

August 24, 2015 11:01 AM

Do you clear the screen before drawing (glClear), does the texture support alpha channel (both the original, and the gl texture you create), if you use custom shader (probably should) does it support the alpha channel (vec4)? Ensure the image loaded in RAM is actually transparent, too (eg print out a pixel in the middle)

glColorPointer is used to se vertice colors not texture colors, you do that in shader, (if you set such i thin k you are only able to pass there 4 components per color) i am not sure if es 1.0 supports ffp but if then vertex alpha color is texture alpha? or sth liek that - not worth trying.

either the way you dont load 32 bit texture properly or your shader (if you have one doesnt output the alpha)

thanks for your reply, im Sure that the textures has the alpha channel, cause when i set the vertex Color to yellow for example, i get this as result:

the problem is if i set the vertex color "Color.Transparent" Both Texture and vertices become Transparent, I want the vertices to be transparent and Just show the texture itself.

(The Color Stores in mBufColors and as is shown in the code called by gl.glColorPointer(4, GLES10.GL_FLOAT, 0, mBufColors); )