1/*
2 * Copyright 2013 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <GLES/gl.h>
18
19#include <cutils/compiler.h>
20
21#include "GLES10RenderEngine.h"
22
23// ---------------------------------------------------------------------------
24namespace android {
25// ---------------------------------------------------------------------------
26
27GLES10RenderEngine::~GLES10RenderEngine() {
28}
29
30void GLES10RenderEngine::setupLayerBlending(
31    bool premultipliedAlpha, bool opaque, int alpha) {
32    // OpenGL ES 1.0 doesn't support texture combiners.
33    // This path doesn't properly handle opaque layers that have non-opaque
34    // alpha values. The alpha channel will be copied into the framebuffer or
35    // screenshot, so if the framebuffer or screenshot is blended on top of
36    // something else,  whatever is below the window will incorrectly show
37    // through.
38    if (CC_UNLIKELY(alpha < 0xFF)) {
39        GLfloat floatAlpha = alpha * (1.0f / 255.0f);
40        if (premultipliedAlpha) {
41            glColor4f(floatAlpha, floatAlpha, floatAlpha, floatAlpha);
42        } else {
43            glColor4f(1.0f, 1.0f, 1.0f, floatAlpha);
44        }
45        glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
46    } else {
47        glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
48    }
49
50    if (alpha < 0xFF || !opaque) {
51        glEnable(GL_BLEND);
52        glBlendFunc(premultipliedAlpha ? GL_ONE : GL_SRC_ALPHA,
53                    GL_ONE_MINUS_SRC_ALPHA);
54    } else {
55        glDisable(GL_BLEND);
56    }
57}
58
59// ---------------------------------------------------------------------------
60}; // namespace android
61// ---------------------------------------------------------------------------
62