Render target blit for Gear VR SDK 1.5.0

DOVREyeSurface.cpp

//==================================================================
/// DOVREyeSurface.cpp
///
/// Created by Davide Pasca - 2017/5/28
/// See the file "license.txt" that comes with this project for
/// copyright info.
//==================================================================

#include "DOVREyeSurface.h"

static const char VERTEX_SHADER[] = R"RAW(
    in vec3 Position;
    in vec2 TexCoord;

    out mediump vec2 v_txc0;

    flat out int flat_viewID;

    uniform mediump vec2 u_scaleST;

    void main()
    {
        gl_Position = vec4( Position, 1.0 );
        v_txc0 = TexCoord * u_scaleST;

        flat_viewID = VIEW_ID;
    }
)RAW";

static const char FRAGMENT_SHADER[] = R"RAW(
    in mediump vec2 v_txc0;
    flat in int flat_viewID;

    uniform lowp sampler2D s_texture0;
    uniform lowp sampler2D s_texture1;

    void main()
    {
        if ( flat_viewID == 0 )
            gl_FragColor = texture( s_texture0, v_txc0 );
        else
            gl_FragColor = texture( s_texture1, v_txc0 );
    }
)RAW";

//==================================================================
DOVREyeSurface::DOVREyeSurface()
{
    // geometry
    OVR::VertexAttribs attribs;

    attribs.uv0.Resize( 4 );
    attribs.uv0[0] = { 0, 1 };
    attribs.uv0[1] = { 1, 1 };
    attribs.uv0[2] = { 0, 0 };
    attribs.uv0[3] = { 1, 0 };

    attribs.position.Resize( 4 );
    attribs.position[0] = { -1,  1, 0 };
    attribs.position[1] = {  1,  1, 0 };
    attribs.position[2] = { -1, -1, 0 };
    attribs.position[3] = {  1, -1, 0 };

    OVR::Array< OVR::TriangleIndex > indices;
    indices.Resize( 6 );
    indices[0] = 0;
    indices[1] = 1;
    indices[2] = 2;
    indices[3] = 2;
    indices[4] = 1;
    indices[5] = 3;

    mGeom.Create( attribs, indices );

    // program
    static OVR::ovrProgramParm sProgParams[] =
    {
        { "s_texture0", OVR::ovrProgramParmType::TEXTURE_SAMPLED },
        { "s_texture1", OVR::ovrProgramParmType::TEXTURE_SAMPLED },
        { "u_scaleST",  OVR::ovrProgramParmType::FLOAT_VECTOR2   },
    };

    mProgram = OVR::GlProgram::Build( VERTEX_SHADER, FRAGMENT_SHADER, sProgParams, 3 );

    // surface
    mSurfaceDef.surfaceName = "DOVREyeSurface";
    {
    auto &gpuState = mSurfaceDef.graphicsCommand.GpuState;
    gpuState.blendEnable = OVR::ovrGpuState::BLEND_DISABLE;
    gpuState.cullEnable = false;
    gpuState.depthEnable = false;
    }
    
    mSurfaceDef.graphicsCommand.UniformData[0].Data = &mTextures[0];
    mSurfaceDef.graphicsCommand.UniformData[1].Data = &mTextures[1];
    mSurfaceDef.graphicsCommand.UniformData[2].Data = &mTexScaleST;

    mSurfaceDef.graphicsCommand.Program = mProgram;
    mSurfaceDef.geo = mGeom;
}

//==================================================================
void DOVREyeSurface::UpdateEyeSurface(
            const std::array<GLuint,2> &texIDs,
            const std::array<float,2> &scaleST )
{
    mTextures[0] = OVR::GlTexture( texIDs[0], 0, 0 );
    mTextures[1] = OVR::GlTexture( texIDs[1], 0, 0 );
    mTexScaleST[0] = scaleST[0];
    mTexScaleST[1] = scaleST[1];
}

//==================================================================
DOVREyeSurface::~DOVREyeSurface()
{
    OVR::GlProgram::Free( mProgram );
    mGeom.Free();
}

DOVREyeSurface.h

//==================================================================
/// DOVREyeSurface.h
///
/// Created by Davide Pasca - 2017/5/28
/// See the file "license.txt" that comes with this project for
/// copyright info.
//==================================================================

#ifndef DOVREYESURFACE_H
#define DOVREYESURFACE_H

#include <array>
#include "SurfaceRender.h"

//==================================================================
class DOVREyeSurface
{
    OVR::ovrSurfaceDef  mSurfaceDef;
    OVR::GlProgram      mProgram;
    OVR::GlGeometry     mGeom;
    OVR::GlTexture      mTextures[2];
    OVR::Vector2f       mTexScaleST = {1,1};

public:
    DOVREyeSurface();
    ~DOVREyeSurface();

    void UpdateEyeSurface(
            const std::array<GLuint,2> &texIDs,
            const std::array<float,2> &scaleST );

    const OVR::ovrSurfaceDef *GetOVRSurfaceDef() const
    {
        return &mSurfaceDef;
    }
};

#endif