Added comments on math stuff
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JonasJan2
parent
3c0b9f42c1
commit
94a01bec41
116
src/matrixMath.c
116
src/matrixMath.c
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@ -8,31 +8,53 @@
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// MATRICES IN COLUMN MAJOR
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// Sets a vector to be (0,0,0)T.
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void vec3Zero(vec3* out) {
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assert(out != NULL);
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for (int i = 0; i < 3; i++) {
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((GLfloat*)out)[i] = 0;
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}
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}
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// Adds two vectors and writes the result into out.
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void vec3Add(vec3* out, vec3* a, vec3* b) {
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assert(a != NULL);
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assert(b != NULL);
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assert(out != NULL);
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for (int i = 0; i < 3; i++) {
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((GLfloat*)out)[i] = ((GLfloat*)a)[i] + ((GLfloat*)b)[i];
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}
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}
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// Multiply a vector by a factor.
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void vec3Multiply(vec3* out, vec3* a, GLfloat x) {
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assert(out != NULL);
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assert(a != NULL);
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for (int i = 0; i < 3; i++) {
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((GLfloat*)out)[i] = ((GLfloat*)a)[i] * x;
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}
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}
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// Divide a vector by another vector.
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void vec3Subtract(vec3* out, vec3* a, vec3* b) {
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assert(out != NULL);
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assert(a != NULL);
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assert(b != NULL);
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vec3 minusB;
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vec3Multiply(&minusB, b, -1);
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vec3Add(out, a, &minusB);
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}
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// Calculates the cross product of two vectors.
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void vec3Cross(vec3* out, vec3* a, vec3* b) {
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assert(out != NULL);
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assert(a != NULL);
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assert(b != NULL);
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vec3 result;
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result.x = a->y * b->z - a->z * b->y;
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result.y = a->z * b->x - a->x * b->z;
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@ -40,19 +62,31 @@ void vec3Cross(vec3* out, vec3* a, vec3* b) {
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memcpy(out, &result, sizeof(vec3));
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}
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// Return the length of a vector.
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GLfloat vec3Length(vec3* a) {
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assert(a != NULL);
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return (GLfloat)sqrt(a->x * a->x + a->y * a->y + a->z * a->z);
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}
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// Return the dot product of a vector.
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GLfloat vec3Dot(vec3* a, vec3* b) {
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assert(a != NULL);
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assert(b != NULL);
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return a->x * b->x + a->y * b->y + a->z * b->z;
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}
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// Normalise a vector.
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void vec3Normalise(vec3* out, vec3* a) {
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assert(out != NULL);
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assert(a != NULL);
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vec3Multiply(out, a, 1 / vec3Length(a));
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}
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// CREATE 4x4 IDENTITY MATRIX
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void identity(mat4* out) {
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assert(out != NULL);
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for (int i = 0; i < 16; i++) {
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((GLfloat*)out)[i] = (i % 4 == i / 4);
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}
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@ -60,6 +94,8 @@ void identity(mat4* out) {
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// CREATE 4x4 TRANSLATION MATRIX
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void translation(mat4* out, vec3* v) {
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assert(out != NULL);
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identity(out);
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out->m03 = v->x;
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out->m13 = v->y;
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@ -68,6 +104,8 @@ void translation(mat4* out, vec3* v) {
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// CREATE 4x4 SCALING MATRIX
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void scaling(mat4* out, vec3* v) {
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assert(out != NULL);
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identity(out);
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out->m00 = v->x;
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out->m11 = v->y;
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@ -81,6 +119,7 @@ void scaling(mat4* out, vec3* v) {
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* 0 0 0 1
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*/
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void rotationZ(mat4* out, GLfloat angle) {
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assert(out != NULL);
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identity(out);
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out->m00 = cos(angle);
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out->m10 = sin(angle);
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@ -95,6 +134,8 @@ void rotationZ(mat4* out, GLfloat angle) {
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* 0 0 0 1
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*/
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void rotationY(mat4* out, GLfloat angle) {
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assert(out != NULL);
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identity(out);
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out->m00 = cos(angle);
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out->m20 = -sin(angle);
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@ -104,6 +145,8 @@ void rotationY(mat4* out, GLfloat angle) {
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// CREATE 4x4 ROTATION MATRIX AROUND Y AXIS
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void rotationX(mat4* out, GLfloat angle) {
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assert(out != NULL);
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identity(out);
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out->m11 = cos(angle);
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out->m21 = sin(angle);
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@ -113,6 +156,10 @@ void rotationX(mat4* out, GLfloat angle) {
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// MULTIPLY ANY TWO MATRICES
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void multiplyAny(GLfloat* out, GLfloat* A, GLfloat* B, int wA, int hA, int wB) {
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assert(out != NULL);
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assert(A != NULL);
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assert(B != NULL);
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int sizeOut = hA * wB;
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GLfloat* result = (GLfloat*) malloc(sizeOut * sizeof(GLfloat));
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for (int i = 0; i < sizeOut; i++) {
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@ -128,11 +175,19 @@ void multiplyAny(GLfloat* out, GLfloat* A, GLfloat* B, int wA, int hA, int wB) {
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// MULTIPLY TWO 4x4 MATRICES
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void multiply(mat4* out, mat4* A, mat4* B) {
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assert(out != NULL);
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assert(A != NULL);
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assert(B != NULL);
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multiplyAny((GLfloat*)out, (GLfloat*)A, (GLfloat*)B, 4, 4, 4);
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}
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// MULTIPLY in WITH TRANSLATION MATRIX OF v
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void translate(mat4* out, mat4* in, vec3* v) {
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assert(out != NULL);
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assert(in != NULL);
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assert(v != NULL);
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mat4 translationMatrix;
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translation(&translationMatrix, v);
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multiply(out, &translationMatrix, in);
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@ -140,6 +195,10 @@ void translate(mat4* out, mat4* in, vec3* v) {
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// MULTIPLY in WITH SCALING MATRIX OF v
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void scale(mat4* out, mat4* in, vec3* v) {
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assert(out != NULL);
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assert(in != NULL);
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assert(v != NULL);
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mat4 scalingMatrix;
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scaling(&scalingMatrix, v);
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multiply(out, &scalingMatrix, in);
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@ -147,18 +206,27 @@ void scale(mat4* out, mat4* in, vec3* v) {
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// MULTIPLY in WITH ROTATION MATRIX OF angle AROUND Z AXIS
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void rotateZ(mat4* out, mat4* in, GLfloat angle) {
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assert(out != NULL);
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assert(in != NULL);
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mat4 rotationMatrix;
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rotationZ(&rotationMatrix, angle);
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multiply(out, &rotationMatrix, in);
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}
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// MULTIPLY in WITH ROTATION MATRIX OF angle AROUND Y AXIS
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void rotateY(mat4* out, mat4* in, GLfloat angle) {
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assert(out != NULL);
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assert(in != NULL);
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mat4 rotationMatrix;
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rotationY(&rotationMatrix, angle);
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multiply(out, &rotationMatrix, in);
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}
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// MULTIPLY in WITH ROTATION MATRIX OF angle AROUND X AXIS
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void rotateX(mat4* out, mat4* in, GLfloat angle) {
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assert(out != NULL);
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assert(in != NULL);
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mat4 rotationMatrix;
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rotationX(&rotationMatrix, angle);
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multiply(out, &rotationMatrix, in);
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@ -166,6 +234,9 @@ void rotateX(mat4* out, mat4* in, GLfloat angle) {
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// TRANSPOSE MATRIX OF ANY SIZE
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void transposeAny(GLfloat* out, GLfloat* in, int w, int h) {
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assert(out != NULL);
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assert(in != NULL);
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int size = w * h;
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GLfloat* result = (GLfloat*) malloc(size * sizeof(GLfloat));
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@ -181,11 +252,15 @@ void transposeAny(GLfloat* out, GLfloat* in, int w, int h) {
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// TRANSPOSE 4x4 MATRIX
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void transpose(mat4* out, mat4* in) {
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assert(out != NULL);
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assert(in != NULL);
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transposeAny((GLfloat*)out, (GLfloat*)in, 4, 4);
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}
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// PRINT MATRIX OF ANY SIZE
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void printAny(GLfloat* M, int w, int h) {
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assert(M != NULL);
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GLfloat* transposed = (GLfloat*) malloc(w * h * sizeof(GLfloat));
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transposeAny(transposed, M, w, h);
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@ -200,19 +275,28 @@ void printAny(GLfloat* M, int w, int h) {
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}
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void vec3Print(vec3* a) {
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assert(a != NULL);
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printAny((GLfloat*)a, 1, 3);
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}
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void mat4Print(mat4* m) {
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assert(m != NULL);
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printAny((GLfloat*)m, 4, 4);
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}
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void mat3Print(mat3* m) {
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assert(m != NULL);
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printAny((GLfloat*)m, 3, 3);
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}
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// TURN mat4 INTO mat3 BY CUTTING LAST COLUMN AND ROW
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void mat3From4(mat3* out, mat4* in) {
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assert(out != NULL);
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assert(in != NULL);
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memcpy(&out->m00, &in->m00, sizeof(vec3));
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memcpy(&out->m01, &in->m01, sizeof(vec3));
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memcpy(&out->m02, &in->m02, sizeof(vec3));
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@ -220,6 +304,9 @@ void mat3From4(mat3* out, mat4* in) {
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// TRANSPOSE 3x3 MATRIX
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void mat3Transpose(mat3* out, mat3* in) {
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assert(out != NULL);
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assert(in != NULL);
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transposeAny((GLfloat*)out, (GLfloat*)in, 3, 3);
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}
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@ -230,6 +317,9 @@ void mat3Transpose(mat3* out, mat3* in) {
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*/
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// GET THE MINOR MATRIX OF A 3x3 MATRIX
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void mat3Minor(mat3* out, mat3* in) {
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assert(out != NULL);
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assert(in != NULL);
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mat3 result;
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result.m00 = in->m11 * in->m22 - in->m21 * in->m12;
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@ -249,6 +339,9 @@ void mat3Minor(mat3* out, mat3* in) {
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// GET THE COFACTOR MATRIX OF A 3x3 MATRIX
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void mat3Cofactor(mat3* out, mat3* in) {
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assert(out != NULL);
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assert(in != NULL);
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mat3 result;
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mat3Minor(out, in);
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@ -260,12 +353,18 @@ void mat3Cofactor(mat3* out, mat3* in) {
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// GET ADJOING MATRRIX OF 3x3 MATRIX
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void mat3Adjoint(mat3* out, mat3* in) {
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assert(out != NULL);
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assert(in != NULL);
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mat3Cofactor(out, in);
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mat3Transpose(out, out);
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}
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// MULTIPLY A 3x3 MATRIX WITH A SCALAR x (componentwise)
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void mat3MultiplyScalar(mat3* out, mat3* in, GLfloat x) {
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assert(out != NULL);
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assert(in != NULL);
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for (int i = 0; i < 9; i++) {
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((GLfloat*)out)[i] = ((GLfloat*)in)[i] * x;
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}
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@ -273,6 +372,8 @@ void mat3MultiplyScalar(mat3* out, mat3* in, GLfloat x) {
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// CALCULATE DETERMINANT OF 3x3 MATRIX
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GLfloat mat3Determinant(mat3* M) {
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assert(M != NULL);
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return
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M->m00 * M->m11 * M->m22
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+ M->m01 * M->m12 * M->m20
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@ -286,6 +387,9 @@ GLfloat mat3Determinant(mat3* M) {
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// GET INVERSE OF 3x3 MATRIX
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void mat3Inverse(mat3* out, mat3* in) {
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assert(out != NULL);
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assert(in != NULL);
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mat3 result;
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mat3Adjoint(&result, in);
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mat3MultiplyScalar(&result, &result, 1 / mat3Determinant(in));
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@ -293,8 +397,11 @@ void mat3Inverse(mat3* out, mat3* in) {
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memcpy(out, &result, sizeof(mat3));
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}
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// GET THE SUM OF DIFFERENCES BETWEEON TWO MATRICES
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// GET THE SUM OF DIFFERENCES BETWEEN TWO MATRICES
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GLfloat sumDiffAny(GLfloat* A, GLfloat* B, int w, int h) {
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assert(A != NULL);
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assert(B != NULL);
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GLfloat result = 0;
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for (int i = 0; i < w * h; i++) {
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result += fabs(A[i] - B[i]);
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@ -304,11 +411,18 @@ GLfloat sumDiffAny(GLfloat* A, GLfloat* B, int w, int h) {
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// GET THE SUM OF DIFFERENCES BETWEEN TWO 3x3 MATRICES
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GLfloat mat3SumDiff(mat3* A, mat3* B) {
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assert(A != NULL);
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assert(B != NULL);
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return sumDiffAny((GLfloat*)A, (GLfloat*)B, 3, 3);
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}
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// COMPONENTWISE SUBTRACT vec2 b FROM vec2 a
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void vec2Subtract(vec2* out, vec2* a, vec2* b) {
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assert(out != NULL);
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assert(a != NULL);
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assert(b != NULL);
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out->x = a->x - b->x;
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out->y = a->y - b->y;
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}
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