GAMES101 作业2 给三角形上色和MSAA的实现

主要代码思路来自大佬：https://blog.csdn.net/qq_36242312/article/details/105758619

然后有个插值计算，好像下节课才讲。

转发的文章的代码不能直接改true来实现MSAA，因为insideTriangle的参数他写的是int，改成float就可以了。

color那里写成t.getColor() * count / 4.0f + (4 - count) * frame_buf[get_index(x,y)] / 4.0f貌似还可以减黑边

static bool insideTriangle(float x, float y, const Vector3f* _v)
{   // TODO : Implement this function to check if the point (x, y) is inside the triangle represented by _v[0], _v[1], _v[2]Eigen::Vector2f p;p<0&&BC[0]*BP[1]-BC[1]*BP[0]>0&&CA[0]*CP[1]-CA[1]*CP[0]>0;}void rst::rasterizer::rasterize_triangle(const Triangle& t) {auto v = t.toVector4();float min_x=std::min(v[0][0],std::min(v[1][0],v[2][0]));float max_x=std::max(v[0][0],std::max(v[1][0],v[2][0]));float min_y=std::min(v[0][1],std::min(v[1][1],v[2][1]));float max_y=std::max(v[0][1],std::max(v[1][1],v[2][1]));min_x=(int)std::floor(min_x);max_x=(int)std::ceil(max_x);min_y=(int)std::floor(min_y);max_y=(int)std::ceil(max_y);bool MSAA=true;if(MSAA){float pos[4][2]={{0.25,0.25},{0.75,0.25},{0.25,0.75},{0.75,0.75},};for(int x=min_x;x<=max_x;x++){for(int y=min_y;y<=max_y;y++){float minDepth=FLT_MAX;int count=0;for(int i=0;i<4;i++){if(insideTriangle((float)x+pos[i][0],(float)y+pos[i][1],t.v)){auto[alpha, beta, gamma] = computeBarycentric2D((float)x+pos[i][0],(float)y+pos[i][1],t.v);float w_reciprocal = 1.0/(alpha / v[0].w() + beta / v[1].w() + gamma / v[2].w());float z_interpolated = alpha * v[0].z() / v[0].w() + beta * v[1].z() / v[1].w() + gamma * v[2].z() / v[2].w();z_interpolated *= w_reciprocal;minDepth=std::min(minDepth,z_interpolated);count++;}}if(count!=0){if(depth_buf[get_index(x,y)]>minDepth){Vector3f color=t.getColor()*(float)count/4.0;Vector3f point;point<<(float)x,(float)y,minDepth;depth_buf[get_index(x,y)]=minDepth;set_pixel(point,color);}}}}}else{for(int x=min_x;x<=max_x;x++){for(int y=min_y;y<=max_y;y++){if(insideTriangle((float)x+0.5,(float)y+0.5,t.v)){auto[alpha, beta, gamma] = computeBarycentric2D((float)x+0.5,(float)y+0.5,t.v);float w_reciprocal = 1.0/(alpha / v[0].w() + beta / v[1].w() + gamma / v[2].w());float z_interpolated = alpha * v[0].z() / v[0].w() + beta * v[1].z() / v[1].w() + gamma * v[2].z() / v[2].w();z_interpolated *= w_reciprocal;if(depth_buf[get_index(x,y)]>z_interpolated){Vector3f color=t.getColor();Vector3f point;point<<(float)x,(float)y,z_interpolated;depth_buf[get_index(x,y)]=z_interpolated;set_pixel(point,color);}}}}}// TODO : Find out the bounding box of current triangle.// iterate through the pixel and find if the current pixel is inside the triangle// If so, use the following code to get the interpolated z value.//auto[alpha, beta, gamma] = computeBarycentric2D(x, y, t.v);//float w_reciprocal = 1.0/(alpha / v[0].w() + beta / v[1].w() + gamma / v[2].w());//float z_interpolated = alpha * v[0].z() / v[0].w() + beta * v[1].z() / v[1].w() + gamma * v[2].z() / v[2].w();//z_interpolated *= w_reciprocal;// TODO : set the current pixel (use the set_pixel function) to the color of the triangle (use getColor function) if it should be painted.
}

                      left is using MSAA   while right is not

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