opengles法线贴图加反射

最新推荐文章于 2021-08-17 23:01:33 发布

原创最新推荐文章于 2021-08-17 23:01:33 发布 · 719 阅读

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本文详细介绍了如何使用OpenGL ES通过shader技术实现法线贴图和物体表面的反射效果，探讨了在移动端图形渲染中如何增强视觉表现。

shader实现

			const char* vs =
			{
				"attribute vec3 inVertex;"//顶点
				"attribute vec3 inNormal;"//法线
				"attribute vec2 inTexCoord;"//纹理
				"attribute vec3 inTangent;"//切线

				"uniform mat4 MVPMatrix;"

				"uniform vec3 EyePosMV;"
				"varying vec3 EyeDirection;"
				"varying vec2 TexCoord;"

				"void main()"
				"{"
				"gl_Position=MVPMatrix*vec4(inVertex,1);"
				"vec3 eyeDirModel=normalize(EyePosMV-inVertex);"//观察方向
				"vec3 binormal=cross(inNormal,inTangent);"//法线和切线向量求叉积
				"mat3 tangentSpaceXform=mat3(inTangent, binormal, inNormal);"//构造BTN矩阵
				"EyeDirection=eyeDirModel*tangentSpaceXform;"
				"TexCoord=inTexCoord;"
				"}"
			};

			const char* ps =
			{
				"precision lowp float;"//指定float的类型为低精度
				"uniform sampler2D sReflectTex;"
				"uniform sampler2D sNormalMap;"

				"varying vec3 EyeDirection;"
				"varying vec2 TexCoord;"

				"void main()"
				"{"
				"vec3 normal=texture2D(sNormalMap,TexCoord).rgb*2.0-1.0;"

				"vec3 reflectDir=reflect(normal,EyeDirection);"//reflect(I, N): I的反射方向， I -2*dot(N, I)*N, N必须先归一化 
				"vec2 reflectCoord=(reflectDir.xy)*0.5+0.5;"

				"gl_FragColor=texture2D(sReflectTex,reflectCoord);"
				"}"

			};

渲染函数

        virtual void    onRender(Program_Perturbed& shader,CELL3RDCamera& camera)
        {
			static float angle = 0;
			matrix4 matRot(1);
			matRot.rotateY(angle);

			matrix4 matTrans;
			matTrans.translate(0,5,0);

			matrix4 matScale(1);
			matScale.scale(0.3f,0.3f,0.3f);

			//总的模型变换矩阵
			matrix4 matModel = matTrans*matRot*matScale;

			angle += 1.0f;

			matrix4 MVP = camera._matProj*camera._matView*matModel;
			matrix4 mv = camera._matView*matModel;
			matrix4 mvI = mv.inverse();

			float4 vEyePosModel;
			vEyePosModel = mvI*float4(0,0,0,1);

			_device.setUniformMatrix4fv(shader.MVPMatrix,1,false,MVP.data());
			_device.setUniform3fv(shader.EyePosModel, 1, &vEyePosModel.x);

			VertexBumpMap* vert = &_arVertexs.front();
			_device.attributePointer(shader.inVertex,3,GL_FLOAT,GL_FALSE,sizeof(VertexBumpMap),vert);
			_device.attributePointer(shader.inNormal, 3, GL_FLOAT, GL_FALSE, sizeof(VertexBumpMap), &vert[0]._normal);
			_device.attributePointer(shader.inTexCoord, 2, GL_FLOAT, GL_FALSE, sizeof(VertexBumpMap), &vert[0]._uv);
			_device.attributePointer(shader.inTangent, 3, GL_FLOAT, GL_FALSE, sizeof(VertexBumpMap), &vert[0]._tangent);

			_device.drawElements(GL_TRIANGLES,_arFaces.size()*3,GL_UNSIGNED_SHORT,&_arFaces.front());
        }