mirror of
https://github.com/bulletphysics/bullet3
synced 2024-12-14 22:00:05 +00:00
118 lines
3.6 KiB
C++
118 lines
3.6 KiB
C++
#include <cmath>
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#include <limits>
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#include <cstdlib>
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#include "our_gl.h"
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#include "Bullet3Common/b3MinMax.h"
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IShader::~IShader() {}
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Matrix viewport(int x, int y, int w, int h)
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{
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Matrix Viewport;
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Viewport = Matrix::identity();
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Viewport[0][3] = x+w/2.f;
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Viewport[1][3] = y+h/2.f;
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Viewport[2][3] = 1.f;
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Viewport[0][0] = w/2.f;
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Viewport[1][1] = h/2.f;
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Viewport[2][2] = 0;
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return Viewport;
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}
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Matrix projection(float coeff) {
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Matrix Projection;
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Projection = Matrix::identity();
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Projection[3][2] = coeff;
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return Projection;
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}
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Matrix lookat(Vec3f eye, Vec3f center, Vec3f up) {
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Vec3f z = (eye-center).normalize();
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Vec3f x = cross(up,z).normalize();
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Vec3f y = cross(z,x).normalize();
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Matrix Minv = Matrix::identity();
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Matrix Tr = Matrix::identity();
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for (int i=0; i<3; i++) {
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Minv[0][i] = x[i];
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Minv[1][i] = y[i];
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Minv[2][i] = z[i];
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Tr[i][3] = -center[i];
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}
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Matrix ModelView;
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ModelView = Minv*Tr;
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return ModelView;
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}
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Vec3f barycentric(Vec2f A, Vec2f B, Vec2f C, Vec2f P) {
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Vec3f s[2];
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for (int i=2; i--; ) {
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s[i][0] = C[i]-A[i];
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s[i][1] = B[i]-A[i];
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s[i][2] = A[i]-P[i];
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}
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Vec3f u = cross(s[0], s[1]);
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if (std::abs(u[2])>1e-2) // dont forget that u[2] is integer. If it is zero then triangle ABC is degenerate
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return Vec3f(1.f-(u.x+u.y)/u.z, u.y/u.z, u.x/u.z);
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return Vec3f(-1,1,1); // in this case generate negative coordinates, it will be thrown away by the rasterizator
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}
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void triangle(mat<4,3,float> &clipc, IShader &shader, TGAImage &image, float *zbuffer, const Matrix& viewPortMatrix)
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{
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triangle(clipc,shader,image,zbuffer,0,viewPortMatrix,0);
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}
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void triangle(mat<4,3,float> &clipc, IShader &shader, TGAImage &image, float *zbuffer, int* segmentationMaskBuffer, const Matrix& viewPortMatrix, int objectIndex) {
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mat<3,4,float> pts = (viewPortMatrix*clipc).transpose(); // transposed to ease access to each of the points
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//we don't clip triangles that cross the near plane, just discard them instead of showing artifacts
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if (pts[0][3]<0 || pts[1][3] <0 || pts[2][3] <0)
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return;
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mat<3,2,float> pts2;
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for (int i=0; i<3; i++) pts2[i] = proj<2>(pts[i]/pts[i][3]);
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Vec2f bboxmin( std::numeric_limits<float>::max(), std::numeric_limits<float>::max());
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Vec2f bboxmax(-std::numeric_limits<float>::max(), -std::numeric_limits<float>::max());
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Vec2f clamp(image.get_width()-1, image.get_height()-1);
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for (int i=0; i<3; i++) {
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for (int j=0; j<2; j++) {
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bboxmin[j] = b3Max(0.f, b3Min(bboxmin[j], pts2[i][j]));
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bboxmax[j] = b3Min(clamp[j], b3Max(bboxmax[j], pts2[i][j]));
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}
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}
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Vec2i P;
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TGAColor color;
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for (P.x=bboxmin.x; P.x<=bboxmax.x; P.x++) {
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for (P.y=bboxmin.y; P.y<=bboxmax.y; P.y++) {
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Vec3f bc_screen = barycentric(pts2[0], pts2[1], pts2[2], P);
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Vec3f bc_clip = Vec3f(bc_screen.x/pts[0][3], bc_screen.y/pts[1][3], bc_screen.z/pts[2][3]);
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bc_clip = bc_clip/(bc_clip.x+bc_clip.y+bc_clip.z);
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float frag_depth = -1*(clipc[2]*bc_clip);
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if (bc_screen.x<0 || bc_screen.y<0 || bc_screen.z<0 ||
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zbuffer[P.x+P.y*image.get_width()]>frag_depth)
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continue;
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bool discard = shader.fragment(bc_clip, color);
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if (!discard) {
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zbuffer[P.x+P.y*image.get_width()] = frag_depth;
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if (segmentationMaskBuffer)
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{
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segmentationMaskBuffer[P.x+P.y*image.get_width()] = objectIndex;
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}
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image.set(P.x, P.y, color);
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}
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}
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}
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}
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