libs/hwui/renderstate/MeshState.h

/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#ifndef RENDERSTATE_MESHSTATE_H
#define RENDERSTATE_MESHSTATE_H

#include "Vertex.h"

#include <GLES2/gl2.h>
#include <GLES2/gl2ext.h>
#include <memory>

namespace android {
namespace uirenderer {

class Program;

// Maximum number of quads that pre-allocated meshes can draw
const uint32_t kMaxNumberOfQuads = 2048;

// This array is never used directly but used as a memcpy source in the
// OpenGLRenderer constructor
const TextureVertex kMeshVertices[] = {
        { 0, 0, 0, 0 },
        { 1, 0, 1, 0 },
        { 0, 1, 0, 1 },
        { 1, 1, 1, 1 },
};

const GLsizei kVertexStride = sizeof(Vertex);
const GLsizei kAlphaVertexStride = sizeof(AlphaVertex);
const GLsizei kTextureVertexStride = sizeof(TextureVertex);

const GLsizei kMeshTextureOffset = 2 * sizeof(float);
const GLsizei kVertexAlphaOffset = 2 * sizeof(float);
const GLsizei kVertexAAWidthOffset = 2 * sizeof(float);
const GLsizei kVertexAALengthOffset = 3 * sizeof(float);
const GLsizei kMeshCount = 4;

class MeshState {
private:
    friend class RenderState;

public:
    ~MeshState();
    ///////////////////////////////////////////////////////////////////////////////
    // Buffer objects
    ///////////////////////////////////////////////////////////////////////////////
    /**
     * Binds the VBO used to render simple textured quads.
     */
    bool bindMeshBuffer();

    /**
     * Binds the specified VBO if needed. If buffer == 0, binds default simple textured quad.
     */
    bool bindMeshBuffer(GLuint buffer);

    /**
     * Unbinds the VBO used to render simple textured quads.
     */
    bool unbindMeshBuffer();

    ///////////////////////////////////////////////////////////////////////////////
    // Vertices
    ///////////////////////////////////////////////////////////////////////////////
    /**
     * Binds an attrib to the specified float vertex pointer.
     * Assumes a stride of gTextureVertexStride and a size of 2.
     */
    void bindPositionVertexPointer(const Program* currentProgram, bool force,
            const GLvoid* vertices, GLsizei stride = kTextureVertexStride);

    /**
     * Binds an attrib to the specified float vertex pointer.
     * Assumes a stride of gTextureVertexStride and a size of 2.
     */
    void bindTexCoordsVertexPointer(const Program* currentProgram, bool force,
            const GLvoid* vertices, GLsizei stride = kTextureVertexStride);

    /**
     * Resets the vertex pointers.
     */
    void resetVertexPointers();
    void resetTexCoordsVertexPointer();

    void enableTexCoordsVertexArray();
    void disableTexCoordsVertexArray();

    ///////////////////////////////////////////////////////////////////////////////
    // Indices
    ///////////////////////////////////////////////////////////////////////////////
    /**
     * Binds a global indices buffer that can draw up to
     * gMaxNumberOfQuads quads.
     */
    bool bindQuadIndicesBuffer();
    bool bindShadowIndicesBuffer();
    bool unbindIndicesBuffer();

private:
    MeshState();
    bool bindIndicesBufferInternal(const GLuint buffer);

    // VBO to draw with
    GLuint meshBuffer;

    GLuint mCurrentBuffer;
    GLuint mCurrentIndicesBuffer;
    GLuint mCurrentPixelBuffer;

    const void* mCurrentPositionPointer;
    GLsizei mCurrentPositionStride;
    const void* mCurrentTexCoordsPointer;
    GLsizei mCurrentTexCoordsStride;

    bool mTexCoordsArrayEnabled;

    // Global index buffer
    GLuint mQuadListIndices;
    GLuint mShadowStripsIndices;
};

} /* namespace uirenderer */
} /* namespace android */

#endif // RENDERSTATE_MESHSTATE_H