Opengles 2.0 multi Textures fade out one by one

Question

I have multi textures, A was drawed on top of B, B was on top of C ...., ( like Picture 1) .I want to fade out A first, then B will appear and fade out either... But when A fade out, background color appeared on top of B, ( like Picture 1 )? Why? What should I do? I have enable Blend like this

glClearColor(0, 104.0/255.0, 55.0/255.0, 1.0); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glEnable(GL_DEPTH_TEST); glEnable(GL_BLEND); glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);

and Fragment shader

"void main(void) { // 2\n"
"gl_FragColor = texture2D(Texture, TexCoordOut);\n"
"gl_FragColor  *= alpha;\n"

" }\n"

Picture 1： background color is green, A and B are both rectangle, A is on top of B

Picure 2 When I fade out A, the result like this:

I aso try to use glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); but it doesn't work either.

**Update 1 shader **

const GLchar *vertex_shader_source_ = { attribute vec4 Position;

uniform mat4 Projection;
uniform mat4 Modelview;

varying vec4 DestinationColor;

attribute vec2 TexCoordIn; // New
varying vec2 TexCoordOut; // New

void main(void) {
    gl_Position = Projection * Modelview *Position;
    TexCoordOut = TexCoordIn;// New

"}

};

const GLchar *fragment_shader_source_ = { uniform highp float alpha; uniform sampler2D Texture;// New

varying highp vec2 TexCoordOut; // New

void main(void) { // 2
gl_FragColor = texture2D(Texture, TexCoordOut);
"gl_FragColor.a  = alpha;

} };

Answer 1

Try with

glDisable(GL_DEPTH_TEST); 

And render the images in back-to-front order.

Most likely the depth test is what's preventing the other images from rendering.