Method drawAt

dgl/src/OpenGL3.cpp:512–563

}

void OpenGLImage::drawAt(const GraphicsContext& context, const Point<int>& pos)
{
    if (textureId == 0 || isInvalid())
        return;

    const OpenGL3GraphicsContext& gl3context = static_cast<const OpenGL3GraphicsContext&>(context);

    if (gl3context.program == 0)
        return;

    if (! setupCalled)
    {
        setupOpenGLImage(*this, textureId);
        setupCalled = true;
    }

    const GLfloat x = (static_cast<double>(pos.getX()) / gl3context.width) * 2 - 1;
    const GLfloat y = (static_cast<double>(pos.getY()) / gl3context.height) * -2 + 1;
    const GLfloat w = (static_cast<double>(getWidth()) / gl3context.width) * 2;
    const GLfloat h = (static_cast<double>(getHeight()) / gl3context.height) * -2;

    const GLfloat color[4] = { 1.0f, 1.0f, 1.0f, 1.0f };
    glUniform4fv(gl3context.color, 1, color);

    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, textureId);
    glUniform1i(gl3context.usingTexture, 1);

    const GLfloat vertices[] = {
        x, y, x, y + h, x + w, y + h, x + w, y,
        0.f, 0.f, 0.f, 1.f, 1.f, 1.f, 1.f, 0.f,
    };
    glBindBuffer(GL_ARRAY_BUFFER, gl3context.buffers[0]);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STREAM_DRAW);
    glEnableVertexAttribArray(gl3context.bounds);
    glEnableVertexAttribArray(gl3context.textureMap);
    glVertexAttribPointer(gl3context.bounds, 2, GL_FLOAT, GL_FALSE, 0, nullptr);
    glVertexAttribPointer(gl3context.textureMap, 2, GL_FLOAT, GL_FALSE, 0, reinterpret_cast<void*>(sizeof(GLfloat) * 8));

    static constexpr const GLubyte order[] = { 0, 1, 2, 0, 2, 3 };
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, gl3context.buffers[1]);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(order), order, GL_STATIC_DRAW);

    glDrawElements(GL_TRIANGLES, ARRAY_SIZE(order), GL_UNSIGNED_BYTE, nullptr);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
    glDisableVertexAttribArray(gl3context.textureMap);
    glDisableVertexAttribArray(gl3context.bounds);
    glUniform1i(gl3context.usingTexture, 0);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindTexture(GL_TEXTURE_2D, 0);
}

#ifdef DGL_USE_GLES
ImageFormat OpenGLImage::getFormat() const noexcept