axmol/cocos/vr/CCVRDistortionMesh.cpp

/****************************************************************************
 Copyright (c) 2016 Google Inc.
 Copyright (c) 2016-2017 Chukong Technologies Inc.

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#include "vr/CCVRDistortionMesh.h"

#include <vector>

#include "vr/CCVRDistortion.h"
#include "math/Vec2.h"
#include "platform/CCGL.h"

NS_CC_BEGIN

DistortionMesh::DistortionMesh(Distortion *distortion,
                               float screenWidth, float screenHeight,
                               float xEyeOffsetScreen, float yEyeOffsetScreen,
                               float textureWidth, float textureHeight,
                               float xEyeOffsetTexture, float yEyeOffsetTexture,
                               float viewportXTexture, float viewportYTexture,
                               float viewportWidthTexture, float viewportHeightTexture,
                               bool vignetteEnabled)
: _indices(-1)
, _arrayBufferID(-1)
, _elementBufferID(-1)
{
    const int rows = 40;
    const int cols = 40;

    GLfloat vertexData[rows * cols * 5];

    int vertexOffset = 0;

    const float vignetteSizeTanAngle = 0.05f;

    const float maxDistance = sqrtf(textureWidth * textureWidth + textureHeight * textureHeight) / 4;

    for (int row = 0; row < rows; row++)
    {
        for (int col = 0; col < cols; col++)
        {
            const float uTexture = col / (cols-1.0f) * (viewportWidthTexture / textureWidth) + viewportXTexture / textureWidth;
            const float vTexture = row / (rows-1.0f) * (viewportHeightTexture / textureHeight) + viewportYTexture / textureHeight;

            const float xTexture = uTexture * textureWidth - xEyeOffsetTexture;
            const float yTexture = vTexture * textureHeight - yEyeOffsetTexture;
            const float rTexture = sqrtf(xTexture * xTexture + yTexture * yTexture) / maxDistance;

            const float textureToScreen = (rTexture > 0.0f) ? distortion->distortInverse(rTexture) / rTexture : 1.0f;

            const float xScreen = xTexture * textureToScreen;
            const float yScreen = yTexture * textureToScreen;

            const float uScreen = (xScreen + xEyeOffsetScreen) / screenWidth;
            const float vScreen = (yScreen + yEyeOffsetScreen) / screenHeight;

            const float vignetteSizeTexture = vignetteSizeTanAngle / textureToScreen;

            const float dxTexture = xTexture + xEyeOffsetTexture - clampf(xTexture + xEyeOffsetTexture,
                                                                         viewportXTexture + vignetteSizeTexture,
                                                                         viewportXTexture + viewportWidthTexture - vignetteSizeTexture);
            const float dyTexture = yTexture + yEyeOffsetTexture - clampf(yTexture + yEyeOffsetTexture,
                                                                         viewportYTexture + vignetteSizeTexture,
                                                                         viewportYTexture + viewportHeightTexture - vignetteSizeTexture);
            const float drTexture = sqrtf(dxTexture * dxTexture + dyTexture * dyTexture);

            float vignette = 1.0f;
            if (vignetteEnabled)
                vignette = 1.0f - clampf(drTexture / vignetteSizeTexture, 0.0f, 1.0f);

            // position x,y (vertices)
            vertexData[(vertexOffset + 0)] = 2.0f * uScreen - 1.0f;
            vertexData[(vertexOffset + 1)] = 2.0f * vScreen - 1.0f;

            // texture u,v
            vertexData[(vertexOffset + 2)] = uTexture;
            vertexData[(vertexOffset + 3)] = vTexture;

            // vignette
            vertexData[(vertexOffset + 4)] = vignette;

            vertexOffset += 5;
        }
    }

    _indices = (rows-1)*cols*2+rows-2;
//    GLshort indexData[_indices];
	std::vector<GLshort> indexData(_indices);
    const int indexDataSize = _indices * sizeof(GLshort);

    int indexOffset = 0;
    vertexOffset = 0;
    for (int row = 0; row < rows-1; row++)
    {
        if (row > 0)
        {
            indexData[indexOffset] = indexData[(indexOffset - 1)];
            indexOffset++;
        }
        for (int col = 0; col < cols; col++)
        {
            if (col > 0)
            {
                if (row % 2 == 0)
                    vertexOffset++;
                else
                    vertexOffset--;
            }
            indexData[(indexOffset++)] = vertexOffset;
            indexData[(indexOffset++)] = (vertexOffset + cols);
        }
        vertexOffset += rows;
    }

    GLuint bufferIDs[2] = { 0, 0 };
    glGenBuffers(2, bufferIDs);
    _arrayBufferID = bufferIDs[0];
    _elementBufferID = bufferIDs[1];

    glBindBuffer(GL_ARRAY_BUFFER, _arrayBufferID);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertexData), vertexData, GL_STATIC_DRAW);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, _elementBufferID);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indexDataSize, &indexData[0], GL_STATIC_DRAW);

    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);

//    GLCheckForError();
}

NS_CC_END