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Ruben 2023-02-24 15:49:56 +01:00
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.gitignore vendored 100644
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# Created by https://www.toptal.com/developers/gitignore/api/c,cmake,vim
# Edit at https://www.toptal.com/developers/gitignore?templates=c,cmake,vim
### C ###
# Prerequisites
*.d
# Object files
*.o
*.ko
*.obj
*.elf
# Linker output
*.ilk
*.map
*.exp
# Precompiled Headers
*.gch
*.pch
# Libraries
*.lib
*.a
*.la
*.lo
# Shared objects (inc. Windows DLLs)
*.dll
*.so
*.so.*
*.dylib
# Executables
*.exe
*.out
*.app
*.i*86
*.x86_64
*.hex
# Debug files
*.dSYM/
*.su
*.idb
*.pdb
# Kernel Module Compile Results
*.mod*
*.cmd
.tmp_versions/
modules.order
Module.symvers
Mkfile.old
dkms.conf
### CMake ###
CMakeLists.txt.user
CMakeCache.txt
CMakeFiles
CMakeScripts
Testing
Makefile
cmake_install.cmake
install_manifest.txt
compile_commands.json
CTestTestfile.cmake
_deps
### CMake Patch ###
# External projects
*-prefix/
### Vim ###
# Swap
[._]*.s[a-v][a-z]
!*.svg # comment out if you don't need vector files
[._]*.sw[a-p]
[._]s[a-rt-v][a-z]
[._]ss[a-gi-z]
[._]sw[a-p]
# Session
Session.vim
Sessionx.vim
# Temporary
.netrwhist
*~
# Auto-generated tag files
tags
# Persistent undo
[._]*.un~
# End of https://www.toptal.com/developers/gitignore/api/c,cmake,vim
build/

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CMakeLists.txt 100644
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cmake_minimum_required(VERSION 3.10)
project(gline C)
set(OpenGL_GL_PREFERENCE "GLVND")
find_package(GLEW REQUIRED)
find_package(OpenGL REQUIRED)
find_package(GLU REQUIRED)
set(GLEW_INCLUDE_PATH "" CACHE PATH "/usr/include/GL")
set(GLFW_INCLUDE_PATH "" CACHE PATH "/usr/include/GLFW")
set(gline_HEADERS
src/gline.h
src/shader.h
src/linmath.h
)
set(gline_SOURCES
src/gline.c
src/shader.c
)
add_executable(
${PROJECT_NAME}
${gline_HEADERS}
${gline_SOURCES}
)
target_include_directories(${PROJECT_NAME} PRIVATE ${GLFW_INCLUDE_DIRS})
target_link_libraries(${PROJECT_NAME} PRIVATE ${OPENGL_LIBRARIES}
${GLU_LIBRARIES} GLEW::GLEW glfw m)
set(CMAKE_BUILD_TYPE Debug)
install(TARGETS ${PROJECT_NAME} RUNTIME DESTINATION bin)

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#version 400
out vec4 frag_color;
void main() {
frag_color = vec4(0.5, 0.0, 0.5, 1.0);
}

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#version 400
in vec3 vp;
void main() {
gl_Position = vec4(vp, 1.0);
}

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src/gline.c 100644
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#include "gline.h"
int main(int argc, char **argv) {
if (!glfwInit()) {
fprintf(stderr, "ERROR: Could not start GLFW\n");
return 1;
}
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow *window = glfwCreateWindow(640, 480, "Gline", NULL, NULL);
if (!window) {
fprintf(stderr, "ERROR: Could not open window\n");
glfwTerminate();
return 1;
}
glfwMakeContextCurrent(window);
glewExperimental = GL_TRUE;
glewInit();
const GLubyte *renderer = glGetString(GL_RENDERER);
const GLubyte *version = glGetString(GL_VERSION);
printf("Renderer: %s\n", renderer);
printf("Version: %s\n", version);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);
float points[] = {0.f, 0.5f, 0.f, 0.5f, -0.5f, 0.f, -0.5f, -0.5f, 0.f};
GLuint vbo = 0;
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, 9 * sizeof(float), points, GL_STATIC_DRAW);
GLuint vao = 0;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, NULL);
const char *vert_source = shader_read_file("../shaders/vertexshader.vert");
const char *frag_source = shader_read_file("../shaders/fragmentshader.frag");
GLuint vs = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vs, 1, &vert_source, NULL);
glCompileShader(vs);
GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fs, 1, &frag_source, NULL);
glCompileShader(fs);
GLuint shader_prog = glCreateProgram();
glAttachShader(shader_prog, fs);
glAttachShader(shader_prog, vs);
glLinkProgram(shader_prog);
while (!glfwWindowShouldClose(window)) {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram(shader_prog);
glBindVertexArray(vao);
glDrawArrays(GL_TRIANGLES, 0, 3);
glfwPollEvents();
glfwSwapBuffers(window);
}
glfwTerminate();
return 0;
}

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src/gline.h 100644
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#ifndef GLINE_H_
#define GLINE_H_
#include "linmath.h"
#include "shader.h"
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <math.h>
#include <stdio.h>
#include <unistd.h>
int main(int argc, char **argv);
#endif

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src/linmath.h 100644
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#ifndef LINMATH_H
#define LINMATH_H
#include <math.h>
#include <string.h>
#ifdef LINMATH_NO_INLINE
#define LINMATH_H_FUNC static
#else
#define LINMATH_H_FUNC static inline
#endif
#define LINMATH_H_DEFINE_VEC(n) \
typedef float vec##n[n]; \
LINMATH_H_FUNC void vec##n##_add(vec##n r, vec##n const a, vec##n const b) { \
int i; \
for (i = 0; i < n; ++i) \
r[i] = a[i] + b[i]; \
} \
LINMATH_H_FUNC void vec##n##_sub(vec##n r, vec##n const a, vec##n const b) { \
int i; \
for (i = 0; i < n; ++i) \
r[i] = a[i] - b[i]; \
} \
LINMATH_H_FUNC void vec##n##_scale(vec##n r, vec##n const v, \
float const s) { \
int i; \
for (i = 0; i < n; ++i) \
r[i] = v[i] * s; \
} \
LINMATH_H_FUNC float vec##n##_mul_inner(vec##n const a, vec##n const b) { \
float p = 0.f; \
int i; \
for (i = 0; i < n; ++i) \
p += b[i] * a[i]; \
return p; \
} \
LINMATH_H_FUNC float vec##n##_len(vec##n const v) { \
return sqrtf(vec##n##_mul_inner(v, v)); \
} \
LINMATH_H_FUNC void vec##n##_norm(vec##n r, vec##n const v) { \
float k = 1.f / vec##n##_len(v); \
vec##n##_scale(r, v, k); \
} \
LINMATH_H_FUNC void vec##n##_min(vec##n r, vec##n const a, vec##n const b) { \
int i; \
for (i = 0; i < n; ++i) \
r[i] = a[i] < b[i] ? a[i] : b[i]; \
} \
LINMATH_H_FUNC void vec##n##_max(vec##n r, vec##n const a, vec##n const b) { \
int i; \
for (i = 0; i < n; ++i) \
r[i] = a[i] > b[i] ? a[i] : b[i]; \
} \
LINMATH_H_FUNC void vec##n##_dup(vec##n r, vec##n const src) { \
int i; \
for (i = 0; i < n; ++i) \
r[i] = src[i]; \
}
LINMATH_H_DEFINE_VEC(2)
LINMATH_H_DEFINE_VEC(3)
LINMATH_H_DEFINE_VEC(4)
LINMATH_H_FUNC void vec3_mul_cross(vec3 r, vec3 const a, vec3 const b) {
r[0] = a[1] * b[2] - a[2] * b[1];
r[1] = a[2] * b[0] - a[0] * b[2];
r[2] = a[0] * b[1] - a[1] * b[0];
}
LINMATH_H_FUNC void vec3_reflect(vec3 r, vec3 const v, vec3 const n) {
float p = 2.f * vec3_mul_inner(v, n);
int i;
for (i = 0; i < 3; ++i)
r[i] = v[i] - p * n[i];
}
LINMATH_H_FUNC void vec4_mul_cross(vec4 r, vec4 const a, vec4 const b) {
r[0] = a[1] * b[2] - a[2] * b[1];
r[1] = a[2] * b[0] - a[0] * b[2];
r[2] = a[0] * b[1] - a[1] * b[0];
r[3] = 1.f;
}
LINMATH_H_FUNC void vec4_reflect(vec4 r, vec4 const v, vec4 const n) {
float p = 2.f * vec4_mul_inner(v, n);
int i;
for (i = 0; i < 4; ++i)
r[i] = v[i] - p * n[i];
}
typedef vec4 mat4x4[4];
LINMATH_H_FUNC void mat4x4_identity(mat4x4 M) {
int i, j;
for (i = 0; i < 4; ++i)
for (j = 0; j < 4; ++j)
M[i][j] = i == j ? 1.f : 0.f;
}
LINMATH_H_FUNC void mat4x4_dup(mat4x4 M, mat4x4 const N) {
int i;
for (i = 0; i < 4; ++i)
vec4_dup(M[i], N[i]);
}
LINMATH_H_FUNC void mat4x4_row(vec4 r, mat4x4 const M, int i) {
int k;
for (k = 0; k < 4; ++k)
r[k] = M[k][i];
}
LINMATH_H_FUNC void mat4x4_col(vec4 r, mat4x4 const M, int i) {
int k;
for (k = 0; k < 4; ++k)
r[k] = M[i][k];
}
LINMATH_H_FUNC void mat4x4_transpose(mat4x4 M, mat4x4 const N) {
// Note: if M and N are the same, the user has to
// explicitly make a copy of M and set it to N.
int i, j;
for (j = 0; j < 4; ++j)
for (i = 0; i < 4; ++i)
M[i][j] = N[j][i];
}
LINMATH_H_FUNC void mat4x4_add(mat4x4 M, mat4x4 const a, mat4x4 const b) {
int i;
for (i = 0; i < 4; ++i)
vec4_add(M[i], a[i], b[i]);
}
LINMATH_H_FUNC void mat4x4_sub(mat4x4 M, mat4x4 const a, mat4x4 const b) {
int i;
for (i = 0; i < 4; ++i)
vec4_sub(M[i], a[i], b[i]);
}
LINMATH_H_FUNC void mat4x4_scale(mat4x4 M, mat4x4 const a, float k) {
int i;
for (i = 0; i < 4; ++i)
vec4_scale(M[i], a[i], k);
}
LINMATH_H_FUNC void mat4x4_scale_aniso(mat4x4 M, mat4x4 const a, float x,
float y, float z) {
vec4_scale(M[0], a[0], x);
vec4_scale(M[1], a[1], y);
vec4_scale(M[2], a[2], z);
vec4_dup(M[3], a[3]);
}
LINMATH_H_FUNC void mat4x4_mul(mat4x4 M, mat4x4 const a, mat4x4 const b) {
mat4x4 temp;
int k, r, c;
for (c = 0; c < 4; ++c)
for (r = 0; r < 4; ++r) {
temp[c][r] = 0.f;
for (k = 0; k < 4; ++k)
temp[c][r] += a[k][r] * b[c][k];
}
mat4x4_dup(M, temp);
}
LINMATH_H_FUNC void mat4x4_mul_vec4(vec4 r, mat4x4 const M, vec4 const v) {
int i, j;
for (j = 0; j < 4; ++j) {
r[j] = 0.f;
for (i = 0; i < 4; ++i)
r[j] += M[i][j] * v[i];
}
}
LINMATH_H_FUNC void mat4x4_translate(mat4x4 T, float x, float y, float z) {
mat4x4_identity(T);
T[3][0] = x;
T[3][1] = y;
T[3][2] = z;
}
LINMATH_H_FUNC void mat4x4_translate_in_place(mat4x4 M, float x, float y,
float z) {
vec4 t = {x, y, z, 0};
vec4 r;
int i;
for (i = 0; i < 4; ++i) {
mat4x4_row(r, M, i);
M[3][i] += vec4_mul_inner(r, t);
}
}
LINMATH_H_FUNC void mat4x4_from_vec3_mul_outer(mat4x4 M, vec3 const a,
vec3 const b) {
int i, j;
for (i = 0; i < 4; ++i)
for (j = 0; j < 4; ++j)
M[i][j] = i < 3 && j < 3 ? a[i] * b[j] : 0.f;
}
LINMATH_H_FUNC void mat4x4_rotate(mat4x4 R, mat4x4 const M, float x, float y,
float z, float angle) {
float s = sinf(angle);
float c = cosf(angle);
vec3 u = {x, y, z};
if (vec3_len(u) > 1e-4) {
vec3_norm(u, u);
mat4x4 T;
mat4x4_from_vec3_mul_outer(T, u, u);
mat4x4 S = {{0, u[2], -u[1], 0},
{-u[2], 0, u[0], 0},
{u[1], -u[0], 0, 0},
{0, 0, 0, 0}};
mat4x4_scale(S, S, s);
mat4x4 C;
mat4x4_identity(C);
mat4x4_sub(C, C, T);
mat4x4_scale(C, C, c);
mat4x4_add(T, T, C);
mat4x4_add(T, T, S);
T[3][3] = 1.f;
mat4x4_mul(R, M, T);
} else {
mat4x4_dup(R, M);
}
}
LINMATH_H_FUNC void mat4x4_rotate_X(mat4x4 Q, mat4x4 const M, float angle) {
float s = sinf(angle);
float c = cosf(angle);
mat4x4 R = {{1.f, 0.f, 0.f, 0.f},
{0.f, c, s, 0.f},
{0.f, -s, c, 0.f},
{0.f, 0.f, 0.f, 1.f}};
mat4x4_mul(Q, M, R);
}
LINMATH_H_FUNC void mat4x4_rotate_Y(mat4x4 Q, mat4x4 const M, float angle) {
float s = sinf(angle);
float c = cosf(angle);
mat4x4 R = {{c, 0.f, -s, 0.f},
{0.f, 1.f, 0.f, 0.f},
{s, 0.f, c, 0.f},
{0.f, 0.f, 0.f, 1.f}};
mat4x4_mul(Q, M, R);
}
LINMATH_H_FUNC void mat4x4_rotate_Z(mat4x4 Q, mat4x4 const M, float angle) {
float s = sinf(angle);
float c = cosf(angle);
mat4x4 R = {{c, s, 0.f, 0.f},
{-s, c, 0.f, 0.f},
{0.f, 0.f, 1.f, 0.f},
{0.f, 0.f, 0.f, 1.f}};
mat4x4_mul(Q, M, R);
}
LINMATH_H_FUNC void mat4x4_invert(mat4x4 T, mat4x4 const M) {
float s[6];
float c[6];
s[0] = M[0][0] * M[1][1] - M[1][0] * M[0][1];
s[1] = M[0][0] * M[1][2] - M[1][0] * M[0][2];
s[2] = M[0][0] * M[1][3] - M[1][0] * M[0][3];
s[3] = M[0][1] * M[1][2] - M[1][1] * M[0][2];
s[4] = M[0][1] * M[1][3] - M[1][1] * M[0][3];
s[5] = M[0][2] * M[1][3] - M[1][2] * M[0][3];
c[0] = M[2][0] * M[3][1] - M[3][0] * M[2][1];
c[1] = M[2][0] * M[3][2] - M[3][0] * M[2][2];
c[2] = M[2][0] * M[3][3] - M[3][0] * M[2][3];
c[3] = M[2][1] * M[3][2] - M[3][1] * M[2][2];
c[4] = M[2][1] * M[3][3] - M[3][1] * M[2][3];
c[5] = M[2][2] * M[3][3] - M[3][2] * M[2][3];
/* Assumes it is invertible */
float idet = 1.0f / (s[0] * c[5] - s[1] * c[4] + s[2] * c[3] + s[3] * c[2] -
s[4] * c[1] + s[5] * c[0]);
T[0][0] = (M[1][1] * c[5] - M[1][2] * c[4] + M[1][3] * c[3]) * idet;
T[0][1] = (-M[0][1] * c[5] + M[0][2] * c[4] - M[0][3] * c[3]) * idet;
T[0][2] = (M[3][1] * s[5] - M[3][2] * s[4] + M[3][3] * s[3]) * idet;
T[0][3] = (-M[2][1] * s[5] + M[2][2] * s[4] - M[2][3] * s[3]) * idet;
T[1][0] = (-M[1][0] * c[5] + M[1][2] * c[2] - M[1][3] * c[1]) * idet;
T[1][1] = (M[0][0] * c[5] - M[0][2] * c[2] + M[0][3] * c[1]) * idet;
T[1][2] = (-M[3][0] * s[5] + M[3][2] * s[2] - M[3][3] * s[1]) * idet;
T[1][3] = (M[2][0] * s[5] - M[2][2] * s[2] + M[2][3] * s[1]) * idet;
T[2][0] = (M[1][0] * c[4] - M[1][1] * c[2] + M[1][3] * c[0]) * idet;
T[2][1] = (-M[0][0] * c[4] + M[0][1] * c[2] - M[0][3] * c[0]) * idet;
T[2][2] = (M[3][0] * s[4] - M[3][1] * s[2] + M[3][3] * s[0]) * idet;
T[2][3] = (-M[2][0] * s[4] + M[2][1] * s[2] - M[2][3] * s[0]) * idet;
T[3][0] = (-M[1][0] * c[3] + M[1][1] * c[1] - M[1][2] * c[0]) * idet;
T[3][1] = (M[0][0] * c[3] - M[0][1] * c[1] + M[0][2] * c[0]) * idet;
T[3][2] = (-M[3][0] * s[3] + M[3][1] * s[1] - M[3][2] * s[0]) * idet;
T[3][3] = (M[2][0] * s[3] - M[2][1] * s[1] + M[2][2] * s[0]) * idet;
}
LINMATH_H_FUNC void mat4x4_orthonormalize(mat4x4 R, mat4x4 const M) {
mat4x4_dup(R, M);
float s = 1.f;
vec3 h;
vec3_norm(R[2], R[2]);
s = vec3_mul_inner(R[1], R[2]);
vec3_scale(h, R[2], s);
vec3_sub(R[1], R[1], h);
vec3_norm(R[1], R[1]);
s = vec3_mul_inner(R[0], R[2]);
vec3_scale(h, R[2], s);
vec3_sub(R[0], R[0], h);
s = vec3_mul_inner(R[0], R[1]);
vec3_scale(h, R[1], s);
vec3_sub(R[0], R[0], h);
vec3_norm(R[0], R[0]);
}
LINMATH_H_FUNC void mat4x4_frustum(mat4x4 M, float l, float r, float b, float t,
float n, float f) {
M[0][0] = 2.f * n / (r - l);
M[0][1] = M[0][2] = M[0][3] = 0.f;
M[1][1] = 2.f * n / (t - b);
M[1][0] = M[1][2] = M[1][3] = 0.f;
M[2][0] = (r + l) / (r - l);
M[2][1] = (t + b) / (t - b);
M[2][2] = -(f + n) / (f - n);
M[2][3] = -1.f;
M[3][2] = -2.f * (f * n) / (f - n);
M[3][0] = M[3][1] = M[3][3] = 0.f;
}
LINMATH_H_FUNC void mat4x4_ortho(mat4x4 M, float l, float r, float b, float t,
float n, float f) {
M[0][0] = 2.f / (r - l);
M[0][1] = M[0][2] = M[0][3] = 0.f;
M[1][1] = 2.f / (t - b);
M[1][0] = M[1][2] = M[1][3] = 0.f;
M[2][2] = -2.f / (f - n);
M[2][0] = M[2][1] = M[2][3] = 0.f;
M[3][0] = -(r + l) / (r - l);
M[3][1] = -(t + b) / (t - b);
M[3][2] = -(f + n) / (f - n);
M[3][3] = 1.f;
}
LINMATH_H_FUNC void mat4x4_perspective(mat4x4 m, float y_fov, float aspect,
float n, float f) {
/* NOTE: Degrees are an unhandy unit to work with.
* linmath.h uses radians for everything! */
float const a = 1.f / tanf(y_fov / 2.f);
m[0][0] = a / aspect;
m[0][1] = 0.f;
m[0][2] = 0.f;
m[0][3] = 0.f;
m[1][0] = 0.f;
m[1][1] = a;
m[1][2] = 0.f;
m[1][3] = 0.f;
m[2][0] = 0.f;
m[2][1] = 0.f;
m[2][2] = -((f + n) / (f - n));
m[2][3] = -1.f;
m[3][0] = 0.f;
m[3][1] = 0.f;
m[3][2] = -((2.f * f * n) / (f - n));
m[3][3] = 0.f;
}
LINMATH_H_FUNC void mat4x4_look_at(mat4x4 m, vec3 const eye, vec3 const center,
vec3 const up) {
/* Adapted from Android's OpenGL Matrix.java. */
/* See the OpenGL GLUT documentation for gluLookAt for a description */
/* of the algorithm. We implement it in a straightforward way: */
/* TODO: The negation of of can be spared by swapping the order of
* operands in the following cross products in the right way. */
vec3 f;
vec3_sub(f, center, eye);
vec3_norm(f, f);
vec3 s;
vec3_mul_cross(s, f, up);
vec3_norm(s, s);
vec3 t;
vec3_mul_cross(t, s, f);
m[0][0] = s[0];
m[0][1] = t[0];
m[0][2] = -f[0];
m[0][3] = 0.f;
m[1][0] = s[1];
m[1][1] = t[1];
m[1][2] = -f[1];
m[1][3] = 0.f;
m[2][0] = s[2];
m[2][1] = t[2];
m[2][2] = -f[2];
m[2][3] = 0.f;
m[3][0] = 0.f;
m[3][1] = 0.f;
m[3][2] = 0.f;
m[3][3] = 1.f;
mat4x4_translate_in_place(m, -eye[0], -eye[1], -eye[2]);
}
typedef float quat[4];
#define quat_add vec4_add
#define quat_sub vec4_sub
#define quat_norm vec4_norm
#define quat_scale vec4_scale
#define quat_mul_inner vec4_mul_inner
LINMATH_H_FUNC void quat_identity(quat q) {
q[0] = q[1] = q[2] = 0.f;
q[3] = 1.f;
}
LINMATH_H_FUNC void quat_mul(quat r, quat const p, quat const q) {
vec3 w, tmp;
vec3_mul_cross(tmp, p, q);
vec3_scale(w, p, q[3]);
vec3_add(tmp, tmp, w);
vec3_scale(w, q, p[3]);
vec3_add(tmp, tmp, w);
vec3_dup(r, tmp);
r[3] = p[3] * q[3] - vec3_mul_inner(p, q);
}
LINMATH_H_FUNC void quat_conj(quat r, quat const q) {
int i;
for (i = 0; i < 3; ++i)
r[i] = -q[i];
r[3] = q[3];
}
LINMATH_H_FUNC void quat_rotate(quat r, float angle, vec3 const axis) {
vec3 axis_norm;
vec3_norm(axis_norm, axis);
float s = sinf(angle / 2);
float c = cosf(angle / 2);
vec3_scale(r, axis_norm, s);
r[3] = c;
}
LINMATH_H_FUNC void quat_mul_vec3(vec3 r, quat const q, vec3 const v) {
/*
* Method by Fabian 'ryg' Giessen (of Farbrausch)
t = 2 * cross(q.xyz, v)
v' = v + q.w * t + cross(q.xyz, t)
*/
vec3 t;
vec3 q_xyz = {q[0], q[1], q[2]};
vec3 u = {q[0], q[1], q[2]};
vec3_mul_cross(t, q_xyz, v);
vec3_scale(t, t, 2);
vec3_mul_cross(u, q_xyz, t);
vec3_scale(t, t, q[3]);
vec3_add(r, v, t);
vec3_add(r, r, u);
}
LINMATH_H_FUNC void mat4x4_from_quat(mat4x4 M, quat const q) {
float a = q[3];
float b = q[0];
float c = q[1];
float d = q[2];
float a2 = a * a;
float b2 = b * b;
float c2 = c * c;
float d2 = d * d;
M[0][0] = a2 + b2 - c2 - d2;
M[0][1] = 2.f * (b * c + a * d);
M[0][2] = 2.f * (b * d - a * c);
M[0][3] = 0.f;
M[1][0] = 2 * (b * c - a * d);
M[1][1] = a2 - b2 + c2 - d2;
M[1][2] = 2.f * (c * d + a * b);
M[1][3] = 0.f;
M[2][0] = 2.f * (b * d + a * c);
M[2][1] = 2.f * (c * d - a * b);
M[2][2] = a2 - b2 - c2 + d2;
M[2][3] = 0.f;
M[3][0] = M[3][1] = M[3][2] = 0.f;
M[3][3] = 1.f;
}
LINMATH_H_FUNC void mat4x4o_mul_quat(mat4x4 R, mat4x4 const M, quat const q) {
/* XXX: The way this is written only works for orthogonal matrices. */
/* TODO: Take care of non-orthogonal case. */
quat_mul_vec3(R[0], q, M[0]);
quat_mul_vec3(R[1], q, M[1]);
quat_mul_vec3(R[2], q, M[2]);
R[3][0] = R[3][1] = R[3][2] = 0.f;
R[0][3] = M[0][3];
R[1][3] = M[1][3];
R[2][3] = M[2][3];
R[3][3] = M[3][3]; // typically 1.0, but here we make it general
}
LINMATH_H_FUNC void quat_from_mat4x4(quat q, mat4x4 const M) {
float r = 0.f;
int i;
int perm[] = {0, 1, 2, 0, 1};
int *p = perm;
for (i = 0; i < 3; i++) {
float m = M[i][i];
if (m < r)
continue;
m = r;
p = &perm[i];
}
r = sqrtf(1.f + M[p[0]][p[0]] - M[p[1]][p[1]] - M[p[2]][p[2]]);
if (r < 1e-6) {
q[0] = 1.f;
q[1] = q[2] = q[3] = 0.f;
return;
}
q[0] = r / 2.f;
q[1] = (M[p[0]][p[1]] - M[p[1]][p[0]]) / (2.f * r);
q[2] = (M[p[2]][p[0]] - M[p[0]][p[2]]) / (2.f * r);
q[3] = (M[p[2]][p[1]] - M[p[1]][p[2]]) / (2.f * r);
}
LINMATH_H_FUNC void mat4x4_arcball(mat4x4 R, mat4x4 const M, vec2 const _a,
vec2 const _b, float s) {
vec2 a;
memcpy(a, _a, sizeof(a));
vec2 b;
memcpy(b, _b, sizeof(b));
float z_a = 0.;
float z_b = 0.;
if (vec2_len(a) < 1.) {
z_a = sqrtf(1. - vec2_mul_inner(a, a));
} else {
vec2_norm(a, a);
}
if (vec2_len(b) < 1.) {
z_b = sqrtf(1. - vec2_mul_inner(b, b));
} else {
vec2_norm(b, b);
}
vec3 a_ = {a[0], a[1], z_a};
vec3 b_ = {b[0], b[1], z_b};
vec3 c_;
vec3_mul_cross(c_, a_, b_);
float const angle = acos(vec3_mul_inner(a_, b_)) * s;
mat4x4_rotate(R, M, c_[0], c_[1], c_[2], angle);
}
#endif

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#include "shader.h"
char *shader_read_file(const char *file_path) {
FILE *fp;
char *buf;
long file_size;
fp = fopen(file_path, "r");
if (fp == NULL) {
fprintf(stderr, "Failed to open file: %s\n", file_path);
return (char *)NULL;
}
fseek(fp, 0, SEEK_END);
file_size = ftell(fp);
fseek(fp, 0, SEEK_SET);
buf = (char *)malloc(file_size + 1);
if (buf == NULL) {
fprintf(stderr, "Failed to allocate memory\n");
fclose(fp);
return (char *)NULL;
}
fread(buf, file_size, 1, fp);
buf[file_size] = '\0';
fclose(fp);
return buf;
}
GLuint load_shader(const char *vfp, const char *ffp) {
GLuint vertex_id = glCreateShader(GL_VERTEX_SHADER);
GLuint fragment_id = glCreateShader(GL_FRAGMENT_SHADER);
char *err = (char *)malloc(sizeof(char *));
char *v_source = shader_read_file(vfp);
char *f_source = shader_read_file(ffp);
if (v_source == NULL) {
fprintf(stderr, "An error occurred\n");
return (GLuint)0;
}
if (f_source == NULL) {
fprintf(stderr, "An error occurred\n");
return (GLuint)0;
}
GLint result = GL_FALSE;
int info_log_len;
printf("Compiling shader: %s\n", vfp);
char const *vc_source = v_source;
glShaderSource(vertex_id, 1, &vc_source, NULL);
glCompileShader(vertex_id);
glGetShaderiv(vertex_id, GL_COMPILE_STATUS, &result);
glGetShaderiv(vertex_id, GL_INFO_LOG_LENGTH, &info_log_len);
if (info_log_len > 0) {
glGetShaderInfoLog(vertex_id, info_log_len, NULL, err);
puts(err);
}
printf("Compiling shader: %s\n", ffp);
char const *fc_source = f_source;
glShaderSource(fragment_id, 1, &fc_source, NULL);
glCompileShader(fragment_id);
glGetShaderiv(fragment_id, GL_COMPILE_STATUS, &result);
glGetShaderiv(vertex_id, GL_INFO_LOG_LENGTH, &info_log_len);
if (info_log_len > 0) {
glGetShaderInfoLog(fragment_id, info_log_len, NULL, err);
puts(err);
}
free(v_source);
free(f_source);
puts("Linking program");
GLuint pid = glCreateProgram();
glAttachShader(pid, vertex_id);
glAttachShader(pid, fragment_id);
glLinkProgram(pid);
glGetProgramiv(pid, GL_LINK_STATUS, &result);
glGetProgramiv(pid, GL_INFO_LOG_LENGTH, &info_log_len);
if (info_log_len > 0) {
glGetShaderInfoLog(pid, info_log_len, NULL, err);
puts(err);
}
free(err);
glDetachShader(pid, vertex_id);
glDetachShader(pid, fragment_id);
glDeleteShader(vertex_id);
glDeleteShader(fragment_id);
return pid;
}

6
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#include <GL/glew.h>
#include <stdio.h>
#include <stdlib.h>
char *shader_read_file(const char *file_path);
GLuint load_shader(const char *vfp, const char *ffp);