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<div class="title">Tutorial 10: Shaders </div> </div>
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<p>This tutorial shows how to use shaders for D3D9, and OpenGL with the engine and how to create new material types with them. It also shows how to disable the generation of mipmaps at texture loading, and how to use text scene nodes.</p>
<p>This tutorial does not explain how shaders work. I would recommend to read the D3D or OpenGL, documentation, to search a tutorial, or to read a book about this.</p>
<p>At first, we need to include all headers and do the stuff we always do, like in nearly all other tutorials: </p><div class="fragment"><div class="line"><span class="preprocessor">#include &lt;irrlicht.h&gt;</span></div><div class="line"><span class="preprocessor">#include &lt;iostream&gt;</span></div><div class="line"><span class="preprocessor">#include &quot;driverChoice.h&quot;</span></div><div class="line"><span class="preprocessor">#include &quot;exampleHelper.h&quot;</span></div><div class="line"></div><div class="line"><span class="keyword">using namespace </span>irr;</div><div class="line"></div><div class="line"><span class="preprocessor">#ifdef _MSC_VER</span></div><div class="line"><span class="preprocessor">#pragma comment(lib, &quot;Irrlicht.lib&quot;)</span></div><div class="line"><span class="preprocessor">#endif</span></div></div><!-- fragment --><p> Because we want to use some interesting shaders in this tutorials, we need to set some data for them to make them able to compute nice colors. In this example, we'll use a simple vertex shader which will calculate the color of the vertex based on the position of the camera. For this, the shader needs the following data: The inverted world matrix for transforming the normal, the clip matrix for transforming the position, the camera position and the world position of the object for the calculation of the angle of light, and the color of the light. To be able to tell the shader all this data every frame, we have to derive a class from the IShaderConstantSetCallBack interface and override its only method, namely OnSetConstants(). This method will be called every time the material is set. The method setVertexShaderConstant() of the IMaterialRendererServices interface is used to set the data the shader needs. If the user chose to use a High Level shader language like HLSL instead of Assembler in this example, you have to set the variable name as parameter instead of the register index. </p><div class="fragment"><div class="line">IrrlichtDevice* device = 0;</div><div class="line"><span class="keywordtype">bool</span> UseHighLevelShaders = <span class="keyword">false</span>;</div><div class="line"></div><div class="line"><span class="keyword">class </span>MyShaderCallBack : <span class="keyword">public</span> video::IShaderConstantSetCallBack</div><div class="line">{</div><div class="line"><span class="keyword">public</span>:</div><div class="line"> MyShaderCallBack() : WorldViewProjID(-1), TransWorldID(-1), InvWorldID(-1), PositionID(-1),</div><div class="line"> ColorID(-1), TextureID(-1), FirstUpdate(true)</div><div class="line"> {</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keyword">virtual</span> <span class="keywordtype">void</span> OnSetConstants(video::IMaterialRendererServices* services,</div><div class="line"> s32 userData)</div><div class="line"> {</div><div class="line"> video::IVideoDriver* driver = services-&gt;getVideoDriver();</div><div class="line"></div><div class="line"> <span class="comment">// get shader constants id.</span></div><div class="line"></div><div class="line"> <span class="keywordflow">if</span> (UseHighLevelShaders &amp;&amp; FirstUpdate)</div><div class="line"> {</div><div class="line"> WorldViewProjID = services-&gt;getVertexShaderConstantID(<span class="stringliteral">&quot;mWorldViewProj&quot;</span>);</div><div class="line"> TransWorldID = services-&gt;getVertexShaderConstantID(<span class="stringliteral">&quot;mTransWorld&quot;</span>);</div><div class="line"> InvWorldID = services-&gt;getVertexShaderConstantID(<span class="stringliteral">&quot;mInvWorld&quot;</span>);</div><div class="line"> PositionID = services-&gt;getVertexShaderConstantID(<span class="stringliteral">&quot;mLightPos&quot;</span>);</div><div class="line"> ColorID = services-&gt;getVertexShaderConstantID(<span class="stringliteral">&quot;mLightColor&quot;</span>);</div><div class="line
<p>The parameters to this method are the following: First, the names of the files containing the code of the vertex and the pixel shader. If you would use addShaderMaterial() instead, you would not need file names, then you could write the code of the shader directly as string. The following parameter is a pointer to the IShaderConstantSetCallBack class we wrote at the beginning of this tutorial. If you don't want to set constants, set this to 0. The last parameter tells the engine which material it should use as base material.</p>
<p>To demonstrate this, we create two materials with a different base material, one with EMT_SOLID and one with EMT_TRANSPARENT_ADD_COLOR. </p><div class="fragment"><div class="line"><span class="comment">// create materials</span></div><div class="line"></div><div class="line">video::IGPUProgrammingServices* gpu = driver-&gt;getGPUProgrammingServices();</div><div class="line">s32 newMaterialType1 = 0;</div><div class="line">s32 newMaterialType2 = 0;</div><div class="line"></div><div class="line"><span class="keywordflow">if</span> (gpu)</div><div class="line">{</div></div><!-- fragment --><p> Create one callback instance for each shader material you add. Reason is that the getVertexShaderConstantID returns ID's which are only valid per added material (The ID's tend to be identical as long as the shader code is exactly identical, but it's not good style to depend on that). </p><div class="fragment"><div class="line"> MyShaderCallBack* mcSolid = <span class="keyword">new</span> MyShaderCallBack();</div><div class="line"> MyShaderCallBack* mcTransparentAdd = <span class="keyword">new</span> MyShaderCallBack();</div><div class="line"></div><div class="line"> <span class="comment">// create the shaders depending on if the user wanted high level</span></div><div class="line"> <span class="comment">// or low level shaders:</span></div><div class="line"></div><div class="line"> <span class="keywordflow">if</span> (UseHighLevelShaders)</div><div class="line"> {</div><div class="line"> <span class="comment">// create material from high level shaders (hlsl, glsl)</span></div><div class="line"></div><div class="line"> newMaterialType1 = gpu-&gt;addHighLevelShaderMaterialFromFiles(</div><div class="line"> vsFileName, <span class="stringliteral">&quot;vertexMain&quot;</span>, video::EVST_VS_1_1,</div><div class="line"> psFileName, <span class="stringliteral">&quot;pixelMain&quot;</span>, video::EPST_PS_1_1,</div><div class="line"> mcSolid, video::EMT_SOLID, 0);</div><div class="line"></div><div class="line"> newMaterialType2 = gpu-&gt;addHighLevelShaderMaterialFromFiles(</div><div class="line"> vsFileName, <span class="stringliteral">&quot;vertexMain&quot;</span>, video::EVST_VS_1_1,</div><div class="line"> psFileName, <span class="stringliteral">&quot;pixelMain&quot;</span>, video::EPST_PS_1_1,</div><div class="line"> mcTransparentAdd, video::EMT_TRANSPARENT_ADD_COLOR, 0);</div><div class="line"> }</div><div class="line"> <span class="keywordflow">else</span></div><div class="line"> {</div><div class="line"> <span class="comment">// create material from low level shaders (asm or arb_asm)</span></div><div class="line"></div><div class="line"> newMaterialType1 = gpu-&gt;addShaderMaterialFromFiles(vsFileName,</div><div class="line"> psFileName, mcSolid, video::EMT_SOLID);</div><div class="line"></div><div class="line"> newMaterialType2 = gpu-&gt;addShaderMaterialFromFiles(vsFileName,</div><div class="line"> psFileName, mcTransparentAdd, video::EMT_TRANSPARENT_ADD_COLOR);</div><div class="line"> }</div><div class="line"></div><div class="line"> mcSolid-&gt;drop();</div><div class="line"> mcTransparentAdd-&gt;drop();</div><div class="line">}</div></div><!-- fragment --><p> Now it's time for testing the materials. We create a test cube and set the material we created. In addition, we add a text scene node to the cube and a rotation animator to make it look more interesting and important. </p><div class="fragment"><div class="line"><span class="comment">// create test scene node 1, with the new created material type 1</span></div><div class="line"></div><div class="line">scene::ISceneNode* node = smgr-&gt;addCubeSceneNode(50);</div><div class="line">node-&gt;setPosition(core::vector3df(0,0,0));</div><div class="line">node-&gt;setMaterialTexture(0, driver-&gt;getTexture(mediaPath + <span class="stringliteral">&quot;wall.bmp&quot;</span>));</div><div class="line">node-&gt;setMa
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