Start tons of small opengl examples

Makefile_many

@@ -53,7 +53,6 @@ OUTS        := $(addprefix $(OUT_DIR), $(OUTS_NODIR))
 all: mkdir $(OUTS)
 	@#TODO ignore errors if not present
 	@if [ -e "$(RUN_INPUT)" ] && [ ! -e "$(OUT_DIR)$(RUN_INPUT)" ]; then ln -s ../$(RUN_INPUT) "$(OUT_DIR)$(RUN_INPUT)"; fi
-	@-$(MAKE) all-post
 ifneq ($(strip $(run)),)
 	@echo
 	cd $(OUT_DIR) && ./"$(run)"

Makefile_one

@@ -47,12 +47,11 @@ TMPS                    := $(addprefix $(TMP_DIR),$(TMPS_NODIR))
 OUT_BASENAME            := $(OUT_BASENAME_NOEXT)$(OUT_EXT)
 OUT                     := $(OUT_DIR)$(OUT_BASENAME)
 
-.PHONY: all all-post assembler clean debug set_debug_flags help mkdir profile set_profile_flags test
+.PHONY: all assembler clean debug set_debug_flags help mkdir profile set_profile_flags test
 
 all: mkdir $(OUT)
 	@#TODO ignore errors if not present
 	@if [ -e "$(RUN_INPUT)" ] && [ ! -e "$(OUT_DIR)$(RUN_INPUT)" ]; then ln -s ../$(RUN_INPUT) "$(OUT_DIR)$(RUN_INPUT)"; fi
-	@-$(MAKE) all-post
 
 $(OUT): $(TMPS)
 	$(MYCXX) $(PROFILE_FLAGS) $^ -o "$@" $(LIBS)

opengl/Makefile_params

@@ -1 +1 @@
-LIBS := -lm -pthread -lGL -lGLU -lglut -lopencv_core -lopencv_imgproc -lopencv_highgui -lopencv_ml -lopencv_video -lopencv_features2d -lopencv_calib3d -lopencv_objdetect -lopencv_contrib -lopencv_legacy -lopencv_flann
+LIBS := -lm -pthread -lGL -lGLU -lglut -lglfw -lX11 -lopencv_core -lopencv_imgproc -lopencv_highgui -lopencv_ml -lopencv_video -lopencv_features2d -lopencv_calib3d -lopencv_objdetect -lopencv_contrib -lopencv_legacy -lopencv_flann

opengl/README.md

@@ -1,10 +1,36 @@
 # OpenGL
 
 1.  [Introduction](introduction.md)
-1.  [glinfo](glinfo.c)
+    1.  [GLUT](glut.md)
+    1.  [Lightning](lightning.md)
+1.  Examples
+    1.  [GLUT hello world](hello_world.c)
+    1.  [glinfo](glinfo.c)
+    1.  [Triangle](triangl.c)
+    1.  [glOrtho](ortho.c)
+    1.  [glShadeModel](shade_model.c)
+    1.  [glViewport](viewport.c)
+    1.  [Depth](depth.c)
+    1.  Transformations
+        1.  [glTranslate](glTranslate.c)
+    1.  Lightning
+        1.  [Ambient](ambient.c)
+        1.  Diffuse
+            1.  [glNormal](normal.c)
+            1.  [Diffuse infinity](diffuse_infinity.c)
+            1.  [Diffuse shadow](diffuse_shadow.c)
+            1.  [Diffuse attenuation](diffuse_attenuation.c)
+    1.  [glDrawPixels (TODO)](draw_pixels.c)
+    1.  [Culling](culling.c)
+    1.  GLUT
+        1. [glutBitmapCharacter](bitmap_character.c)
+    1.  [GLX](glx.c)
+    1.  Performance
+        1.  [Many triangles](many_triangles.c)
 1.  [main](main.cpp)
-1.  bouncing_balls
-    1. [one](bouncing_balls_one.cpp)
-    1. [many](bouncing_balls_many.cpp)
-1.  [Texture FPS](texture_fps.cpp)
+1.  Mini projects
+    1.  bouncing_balls
+        1. [one](bouncing_balls_one.cpp)
+        1. [many](bouncing_balls_many.cpp)
+    1.  [Texture FPS](texture_fps.cpp)
 1.  [Bibliography](bibliography.md)

opengl/TODO.md

@@ -2,3 +2,35 @@
 
 -   Are the OpenGL types fixed size? How to properly printf them?
 -   How to select the rendering device? <http://stackoverflow.com/questions/6036292/select-a-graphic-device-in-windows-opengl> `prime-select`?
+-   Do everything without GLUT for Linux to learn what is going on. Windowing and events are likely not worth the trouble...
+    -   <http://stackoverflow.com/questions/879035/initializing-opengl-without-glut>
+    -   <http://stackoverflow.com/questions/5608767/learning-opengl-without-glut>
+    -   <https://www.opengl.org/discussion_boards/showthread.php/177999-GCC-OpenGL-without-glut>
+-   Understand the matrix stack, `glLoadMatrixg`. Major application: define new points relative to the previous view. E.g.: wheels of a car relative to the car.
+    - <http://gamedev.stackexchange.com/questions/72044/why-do-we-use-4x4-matrices-to-transform-things-in-3d>
+    - <http://stackoverflow.com/questions/13647108/matrix-stacks-in-opengl-deprecated>
+    - <http://stackoverflow.com/questions/3755998/what-is-the-point-of-the-matrix-stack-in-opengl>
+    - <http://gamedev.stackexchange.com/questions/83725/new-to-opengl-having-trouble-understanding-matrix-transformation>
+    - <https://www.reddit.com/r/learnprogramming/comments/1sipqz/why_does_opengl_use_4x4_matrices_to_describe_3d/>
+
+    1) Why use matrices at all? Answer: to pre-calculate multiple combined operations.
+    2) Why 4D for 3D objects? Let's see 3D for 2D and then we're done.
+
+    TODO: world, view and projection transforms?
+-   Make image spin with mouse drag:
+    - http://stackoverflow.com/questions/19884182/moving-a-drawing-around-in-opengl-with-mouse
+    - http://stackoverflow.com/questions/16342442/drag-and-drop-of-images-using-opengl-c
+    - http://stackoverflow.com/questions/20288861/mouse-drag-object-in-opengl-glut
+    - http://stackoverflow.com/questions/5734794/mouse-movement-opengl
+    - http://stackoverflow.com/questions/1426415/opengl-moving-camera-with-mouse
+    - http://gamedev.stackexchange.com/questions/53333/how-to-implement-a-basic-arcball-camera-in-opengl-with-glm
+-   VAO, VBO http://stackoverflow.com/questions/11821336/what-are-vertex-array-objects
+    -   Immediate mode vs retained mode:
+        - immediate mode is deprecated. So like, glBegin, glEnd and glVertex which we use in every test program are deprecated. Lol.
+        - http://gamedev.stackexchange.com/questions/21733/why-does-opengl-3-only-allow-vbos
+        - http://stackoverflow.com/questions/6733934/what-does-immediate-mode-mean-in-opengl Hello world requested but not provided, too long, lol. Opportunity!
+        - http://gamedev.stackexchange.com/questions/21733/why-does-opengl-3-only-allow-vbos
+-   https://en.wikipedia.org/wiki/Stencil_buffer
+-   shading
+    - vertex shader
+    - fragment shader

opengl/ambient.c

@@ -0,0 +1,59 @@
+/*
+The triangle only becomes gray because ambient light is halved:
+http://forum.unity3d.com/threads/why-is-ambient-light-at-half-strength.33955/
+*/
+
+#include <stdlib.h>
+
+#include <GL/gl.h>
+#include <GL/glu.h>
+#include <GL/glut.h>
+
+static void init(void) {
+    GLfloat light0_ambient[] = {1.0, 1.0, 1.0, 1.0};
+    GLfloat light0_position[] = {0.0, -1.0, 0.0, 0.0};
+    glClearColor(0.0, 0.0, 0.0, 0.0);
+    glShadeModel(GL_SMOOTH);
+    glEnable(GL_LIGHTING);
+    glLightfv(GL_LIGHT0, GL_POSITION, light0_position);
+    glLightfv(GL_LIGHT0, GL_AMBIENT, light0_ambient);
+    glColorMaterial(GL_FRONT, GL_AMBIENT);
+    glEnable(GL_COLOR_MATERIAL);
+}
+
+static void draw_triangle() {
+    glColor3f(1.0, 0.0, 0.0);
+    glVertex3f(0.0f, 1.0f, 0.0f);
+    glVertex3f(-1.0f, -1.0f, 0.0f);
+    glVertex3f(1.0f, -1.0f, 0.0f);
+}
+
+static void display(void) {
+    glClear(GL_COLOR_BUFFER_BIT);
+    glLoadIdentity();
+    glBegin(GL_TRIANGLES);
+    draw_triangle();
+    glEnd();
+    glFlush();
+}
+
+static void reshape(int w, int h) {
+    glViewport(0, 0, w, h);
+    glMatrixMode(GL_PROJECTION);
+    glLoadIdentity();
+    glOrtho(-2.0, 2.0, -2.0, 2.0, -1.0, 1.0);
+    glMatrixMode(GL_MODELVIEW);
+}
+
+int main(int argc, char** argv) {
+    glutInit(&argc, argv);
+    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
+    glutInitWindowSize(500, 500);
+    glutInitWindowPosition(100, 100);
+    glutCreateWindow(argv[0]);
+    init();
+    glutDisplayFunc(display);
+    glutReshapeFunc(reshape);
+    glutMainLoop();
+    return EXIT_SUCCESS;
+}

opengl/bibliography.md

@@ -1,12 +1,28 @@
 # Bibliography
 
+Standards:
+
 -   <https://www.opengl.org/registry/#oldspecs> Khronos standards
 
     From there you can reach for example:
 
     - <https://www.opengl.org/registry/doc/glspec21.20061201.pdf> 2.1 spec
     - <https://www.opengl.org/sdk/docs/man2/> 2.1 online reference
 
--   Demos:
+Tutorials with code:
+
+- <https://github.com/JoeyDeVries/LearnOpenGL> <http://learnopengl.com/>
+- <https://github.com/opengl-tutorials/ogl>
+- <https://github.com/capnramses/antons_opengl_tutorials_book> Some hardcore examples. Uses GLFW.
+- <https://github.com/Overv/Open.GL/tree/master/content/code>
+- <http://www.glprogramming.com/red/>
+- <https://github.com/tomdalling/opengl-series> <http://www.tomdalling.com/blog/category/modern-opengl/> Modern, no immediate rendering.
+- <http://www.videotutorialsrock.com/opengl_tutorial/normalize/video.php>
+
+Java:
+
+- <https://github.com/OskarVeerhoek/YouTube-tutorials>
+
+Demos:
 
-    - <https://github.com/prideout/recipes>
+- <https://github.com/prideout/recipes>

opengl/bitmap_character.c

@@ -0,0 +1,72 @@
+/*
+# glutBitmapCharacter
+
+http://stackoverflow.com/questions/8847899/opengl-how-to-draw-text-using-only-opengl-methods
+*/
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <GL/gl.h>
+#include <GL/glu.h>
+#include <GL/glut.h>
+
+static void init() {
+    glEnable(GL_DEPTH_TEST);
+    glClearColor(0.0, 0.0, 0.0, 0.0);
+    glShadeModel(GL_FLAT);
+}
+
+static void drawString (void *font, char *s, GLfloat x, GLfloat y, GLfloat z){
+    unsigned int i;
+    /* Must come before glRasterPos. */
+    glColor3f(0.0f, 0.0f, 1.0f);
+    glRasterPos3f(x, y, z);
+    for (i = 0; i < strlen(s); i++)
+        glutBitmapCharacter(font, s[i]);
+}
+
+static void display(void) {
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+    glLoadIdentity();
+    gluLookAt(0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
+    glBegin(GL_TRIANGLES);
+    glColor3f(1.0f, 0.0f, 0.0f);
+    glVertex3f( 0.0f, 1.0f, 0.0f);
+    glVertex3f(-1.0f, -1.0f, 0.0f);
+    glVertex3f( 1.0f, -1.0f, 0.0f);
+    glEnd();
+
+    /* This is drawn as close as possible to the camera. */
+    drawString(GLUT_BITMAP_HELVETICA_18, "bottom", -1.0, -1.0, 3.5);
+
+    /* Depth is considered. Things that come behind are hidden. */
+    drawString(GLUT_BITMAP_HELVETICA_18, "behind", 0.0, 0.0, -1.0);
+    drawString(GLUT_BITMAP_HELVETICA_18, "front", 0.0, 0.5, 1.0);
+
+    /* The font size is fixed no matter how far back we are.*/
+    drawString(GLUT_BITMAP_HELVETICA_18, "far", 200.0, 200.0, -990.0);
+
+    glFlush();
+}
+
+static void reshape(int w, int h) {
+    glViewport(0, 0, w, h);
+    glMatrixMode(GL_PROJECTION);
+    glLoadIdentity();
+    glFrustum(-1.0, 1.0, -1.0, 1.0, 1.5, 1000.0);
+    glMatrixMode(GL_MODELVIEW);
+}
+
+int main(int argc, char** argv) {
+    glutInit(&argc, argv);
+    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
+    glutInitWindowSize(500, 500);
+    glutInitWindowPosition(100, 100);
+    glutCreateWindow(argv[0]);
+    init();
+    glutDisplayFunc(display);
+    glutReshapeFunc(reshape);
+    glutMainLoop();
+    return EXIT_SUCCESS;
+}

opengl/bouncing_balls_many.cpp

@@ -2,7 +2,10 @@
 Many spheres bouncing inside a cube with gravity,
 energy dissipation on impact, and impact between the spheres.
 
-TODO: DRY up with bouncing_balls_one.cpp
+TODO: DRY
+
+- up with bouncing_balls_one.cpp
+- balls flicker a lot. Why?
 */
 
 #include <cstdio>
@@ -171,9 +174,6 @@ void calc_new_scene(void){
 }
 
 void draw_cube(){
-
-    glPushMatrix();
-
     glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
     glColor3fv(DARK_GRAY);
 
@@ -214,8 +214,6 @@ void draw_cube(){
     glLineWidth(2.0);
     glutWireCube(2.0);
 
-    glPopMatrix();
-
 }
 
 void draw_spheres() {

opengl/bouncing_balls_one.cpp

@@ -63,7 +63,7 @@ void calc_new_scene(void) {
     old_t = t;
 
     // Calculate new scene based on dt (ms).
-    for (int i = 0; i<total_spheres; i++){
+    for (int i = 0; i < total_spheres; ++i){
 
         //cout << "\n---------------------------\n";
         //cout << "center\n" << spheres[i].center.str() << "\n";
@@ -83,14 +83,10 @@ void calc_new_scene(void) {
             spheres[i].speed = spheres[i].speed + GRAVITY*dt;
         }
     }
-
     glutPostRedisplay();
 }
 
 void draw_cube(){
-
-    glPushMatrix();
-
     glColor3fv(DARK_GRAY);
 
     // back
@@ -129,33 +125,25 @@ void draw_cube(){
     glColor3fv(WHITE);
     glLineWidth(2.0);
     glutWireCube(2.0);
-
-    glPopMatrix();
-
 }
 
 void draw_spheres() {
     for (int i=0; i<total_spheres; i++){
         spheres[i].draw();
     }
-
 }
 
 void draw_scene(void) {
-
     glLoadIdentity();
     gluLookAt(eyex, eyey, eyez, centerx, centery, centerz, upx, upy, upz);
-
     draw_cube();
     draw_spheres();
-
 }
 
 void display(void) {
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
     draw_scene();
     glutSwapBuffers();
-
 }
 
 void reshape(int w, int h) {
@@ -180,7 +168,7 @@ int main(int argc, char** argv) {
     glutInitWindowSize(500, 500);
     glutInitWindowPosition(100, 100);
     glutCreateWindow(argv[0]);
-    glClearColor(clear_color_r,clear_color_g,clear_color_b,1.0);
+    glClearColor(clear_color_r, clear_color_g, clear_color_b, 1.0);
     glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
     glEnable(GL_POLYGON_OFFSET_FILL);
     glEnable(GL_POLYGON_OFFSET_LINE);

opengl/configure

@@ -1,3 +1,3 @@
 #!/usr/bin/env bash
 sudo aptitude update
-sudo aptitude install -y freeglut3-dev libopencv-dev
+sudo aptitude install -y freeglut3-dev libglfw3-dev libopencv-dev