examples

commit b1cf63a36c74da863cb66b9aa9bb7e50b2dc76fe
parent 7d6ab667ba562573e922a302b350e4d834c22f9a
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Fri, 14 Apr 2023 23:06:54 +0100

gl: Add simple 3D and lighting examples

Diffstat:
M
Tupfile
 | 
2
++
A
src/gl-3d.c
 | 
122
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A
src/gl-lighting.c
 | 
191
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

3 files changed, 315 insertions(+), 0 deletions(-)
diff --git a/Tupfile b/Tupfile
@@ -6,6 +6,8 @@ CXXFLAGS = -std=c++20 $(COMMON_FLAGS)
 LDLIBS_aio = -lrt
 LDLIBS_alsa-simple = -lasound
 LDLIBS_gl = -lglfw -lGL
+LDLIBS_gl-3d = -lglfw -lGL -lm
+LDLIBS_gl-lighting = -lglfw -lGL -lm
 LDLIBS_gl-asteroids = -lglfw -lGL -lm -lasound
 LDLIBS_io_uring = -luring
 LDLIBS_pulse-async-client = -lpulse
diff --git a/src/gl-3d.c b/src/gl-3d.c
@@ -0,0 +1,122 @@
+#include <GLFW/glfw3.h>
+#include <assert.h>
+#include <math.h>
+
+#define DEFAULT_W 800
+#define DEFAULT_H 450
+
+#define ENABLE_GUARD(x)  glEnable(x); for (int i = 1; i--; glDisable(x))
+#define MATRIX_GUARD glPushMatrix(); for (int i = 1; i--; glPopMatrix())
+#define PROJECTION_GUARD glMatrixMode(GL_PROJECTION); for (int i = 1; i--; glMatrixMode(GL_MODELVIEW))
+
+struct vertex
+{
+	float colour[3];
+	float vertex[3];
+} const octahedron_vertices[6] =
+{
+	{{0,0,1}, {0  ,0  , .5}},
+	{{0,1,0}, {0  , .5,  0}},
+	{{0,1,1}, {-.5,0  ,  0}},
+	{{1,0,1}, {0  ,-.5,  0}},
+	{{1,0,0}, { .5,  0,  0}},
+	{{1,1,0}, {0  ,0  ,-.5}},
+};
+
+unsigned char const octahedron_indices[] =
+{
+	0,1,2,3,4,1,
+	5,4,3,2,1,4,
+};
+
+static void draw_octahedron()
+{
+	glInterleavedArrays(GL_C3F_V3F, 0, octahedron_vertices);
+	glDrawElements(GL_TRIANGLE_FAN, 6, GL_UNSIGNED_BYTE, octahedron_indices + 0);
+	glDrawElements(GL_TRIANGLE_FAN, 6, GL_UNSIGNED_BYTE, octahedron_indices + 6);
+}
+
+static void key_cb(GLFWwindow* w, int key, int /*scancode*/, int action, int /*mods*/)
+{
+	if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
+		glfwSetWindowShouldClose(w, GLFW_TRUE);
+}
+
+static void set_frustum_size(int w, int h)
+{
+	double fru_horz = w / sqrt(w*w + h*h);
+	double fru_vert = h / sqrt(w*w + h*h);
+
+	PROJECTION_GUARD
+	{
+		glLoadIdentity();
+		glFrustum(-fru_horz, fru_horz, -fru_vert, fru_vert, 1.5, 8);
+		glTranslated(0, 0, -5);
+	}
+}
+
+static void fb_resize_cb(GLFWwindow*, int w, int h)
+{
+	glViewport(0, 0, w, h);
+	set_frustum_size(w, h);
+}
+
+int main(int, char* argv[])
+{
+	assert(glfwInit());
+	GLFWwindow* window = glfwCreateWindow(DEFAULT_W, DEFAULT_H, argv[0], NULL, NULL);
+	assert(window);
+	glfwMakeContextCurrent(window);
+	set_frustum_size(DEFAULT_W, DEFAULT_H);
+	glfwSetKeyCallback(window, key_cb);
+	glfwSetFramebufferSizeCallback(window, fb_resize_cb);
+	glfwSwapInterval(1);
+	glClearColor(0, 0, 0, 1);
+	glEnable(GL_CULL_FACE);
+	glEnable(GL_DEPTH_TEST);
+
+	while (!glfwWindowShouldClose(window))
+	{
+		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+		double t = glfwGetTime() / 8;
+		double turns = t * 6.283185307;
+		double deg = t * 360;
+
+		glLoadIdentity();
+		glTranslated(0, -.2, 0);
+		glRotated(-60, 1, 0, 0);
+		glRotated(deg / 7, 0, 0, 1);
+
+		MATRIX_GUARD
+		{
+			glRotated(deg, 0, 0, 1);
+			draw_octahedron();
+		}
+
+		MATRIX_GUARD
+		{
+			glTranslated(0, 0, 1);
+			glRotated(90, 0, 0, 1);
+			draw_octahedron();
+		}
+
+		MATRIX_GUARD
+		{
+			glTranslated(0, 0, -1);
+			glRotated(-90, 0, 0, 1);
+			draw_octahedron();
+		}
+
+		MATRIX_GUARD
+		{
+			glTranslated(sin(2*turns), cos(2*turns), sin(turns));
+			glRotated(180+deg, 0, 0, 1);
+			draw_octahedron();
+		}
+
+		glfwSwapBuffers(window);
+		glfwPollEvents();
+	}
+	glfwTerminate(); /* Implicit window destroy */
+}
diff --git a/src/gl-lighting.c b/src/gl-lighting.c
@@ -0,0 +1,191 @@
+#include <GLFW/glfw3.h>
+#include <assert.h>
+#include <math.h>
+
+#define DEFAULT_W 800
+#define DEFAULT_H 450
+
+#define ARRAY_SIZE(a)    (sizeof(a) / sizeof(*(a)))
+#define FOR_EACH(a, x)   for (typeof(&*(a)) x = a; x < (a) + ARRAY_SIZE(a); ++x)
+
+#define ENABLE_GUARD(x)  glEnable(x); for (int i = 1; i--; glDisable(x))
+#define MATRIX_GUARD     glPushMatrix(); for (int i = 1; i--; glPopMatrix())
+#define PROJECTION_GUARD glMatrixMode(GL_PROJECTION); for (int i = 1; i--; glMatrixMode(GL_MODELVIEW))
+#define DRAW_GUARD(mode) glBegin(mode); for (int i = 1; i--; glEnd())
+
+struct vertex
+{
+	float colour[3];
+	float vertex[3];
+} const octahedron_vertices[6] =
+{
+	{{0,0,1}, {0  ,0  , .5}},
+	{{0,1,0}, {0  , .5,  0}},
+	{{0,1,1}, {-.5,0  ,  0}},
+	{{1,0,1}, {0  ,-.5,  0}},
+	{{1,0,0}, { .5,  0,  0}},
+	{{1,1,0}, {0  ,0  ,-.5}},
+};
+
+struct triangle
+{
+	float normal[3];
+	unsigned char index[3];
+} const octahedron_triangles[8] = {
+	{{-1, 1, 1}, {0,1,2}},
+	{{-1,-1, 1}, {0,2,3}},
+	{{ 1,-1, 1}, {0,3,4}},
+	{{ 1, 1, 1}, {0,4,1}},
+	{{ 1, 1,-1}, {5,1,4}},
+	{{ 1,-1,-1}, {5,4,3}},
+	{{-1,-1,-1}, {5,3,2}},
+	{{-1, 1,-1}, {5,2,1}},
+};
+
+static void draw_octahedron()
+{
+	glInterleavedArrays(GL_C3F_V3F, 0, octahedron_vertices);
+	FOR_EACH (octahedron_triangles, t)
+	{
+		glNormal3fv(t->normal);
+		glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_BYTE, t->index);
+	}
+}
+
+static void key_cb(GLFWwindow* w, int key, int /*scancode*/, int action, int /*mods*/)
+{
+	if (action != GLFW_PRESS)
+		return;
+	switch (key)
+	{
+	case GLFW_KEY_ESCAPE:
+		glfwSetWindowShouldClose(w, GLFW_TRUE);
+		return;
+	case GLFW_KEY_F11:
+		GLFWmonitor* monitor = glfwGetWindowMonitor(w);
+		if (!monitor)
+		{
+			monitor = glfwGetPrimaryMonitor();
+			GLFWvidmode const* mode = glfwGetVideoMode(monitor);
+			glfwSetWindowMonitor(w, monitor, 0, 0, mode->width, mode->height, mode->refreshRate);
+		} else
+			glfwSetWindowMonitor(w, NULL, 0, 0, DEFAULT_W, DEFAULT_H, GLFW_DONT_CARE);
+		return;
+	case GLFW_KEY_F10:
+		return;
+	}
+}
+
+static void set_frustum_size(int w, int h)
+{
+	double fru_horz = w / sqrt(w*w + h*h);
+	double fru_vert = h / sqrt(w*w + h*h);
+
+	PROJECTION_GUARD
+	{
+		glLoadIdentity();
+		glFrustum(-fru_horz, fru_horz, -fru_vert, fru_vert, 1.5, 8);
+		glTranslated(0, 0, -5);
+	}
+}
+
+static void fb_resize_cb(GLFWwindow*, int w, int h)
+{
+	glViewport(0, 0, w, h);
+	set_frustum_size(w, h);
+}
+
+static float const ambient_light[4] = {.1, .1, .1, 1};
+static float const light_colour[4] = {1, 1, 1, 1};
+static float const material_specular[4] = {.000001, .000001, .000001, 1};
+static float light_position0[4] = {0, 0, 1, 1};
+static float light_position1[4] = {-.5, -.5, 1.6, 1};
+
+int main(int, char* argv[])
+{
+	assert(glfwInit());
+	GLFWwindow* window = glfwCreateWindow(DEFAULT_W, DEFAULT_H, argv[0], NULL, NULL);
+	assert(window);
+	glfwMakeContextCurrent(window);
+	set_frustum_size(DEFAULT_W, DEFAULT_H);
+	glfwSetKeyCallback(window, key_cb);
+	glfwSetFramebufferSizeCallback(window, fb_resize_cb);
+	glfwSwapInterval(1);
+	glClearColor(0, 0, 0, 1);
+	glEnable(GL_CULL_FACE);
+	glEnable(GL_DEPTH_TEST);
+	glEnable(GL_RESCALE_NORMAL);
+
+	for (GLuint light = GL_LIGHT0; light <= GL_LIGHT1; ++light)
+	{
+		glEnable(light);
+		glLightfv(light, GL_DIFFUSE, light_colour);
+		glLightfv(light, GL_SPECULAR, light_colour);
+	}
+
+	glLightModelfv(GL_LIGHT_MODEL_AMBIENT, ambient_light);
+
+	glEnable(GL_COLOR_MATERIAL);
+	glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE);
+	glMateriali(GL_FRONT_AND_BACK, GL_SHININESS, 24);
+	glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, material_specular);
+	glPointSize(10);
+	glEnable(GL_POINT_SMOOTH);
+
+	while (!glfwWindowShouldClose(window))
+	{
+		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+		double t = glfwGetTime() / 8;
+		double turns = t * 6.283185307;
+		double deg = t * 360;
+
+		glLoadIdentity();
+		glTranslated(0, -.2, 0);
+		glRotated(-60, 1, 0, 0);
+		glRotated(deg / 7, 0, 0, 1);
+
+		light_position0[0] = -sin(2*turns)*1.5;
+		light_position0[1] = -cos(2*turns)*1.5;
+
+		glLightfv(GL_LIGHT0, GL_POSITION, light_position0);
+		glLightfv(GL_LIGHT1, GL_POSITION, light_position1);
+
+		DRAW_GUARD(GL_POINTS)
+			glColor4fv(light_colour), glVertex4fv(light_position0), glVertex4fv(light_position1);
+
+		ENABLE_GUARD(GL_LIGHTING)
+		{
+			MATRIX_GUARD
+			{
+				glRotated(deg, 0, 0, 1);
+				draw_octahedron();
+			}
+
+			MATRIX_GUARD
+			{
+				glTranslated(0, 0, 1);
+				glRotated(90, 0, 0, 1);
+				draw_octahedron();
+			}
+
+			MATRIX_GUARD
+			{
+				glTranslated(0, 0, -1);
+				glRotated(-90, 0, 0, 1);
+				draw_octahedron();
+			}
+
+			MATRIX_GUARD
+			{
+				glTranslated(sin(2*turns), cos(2*turns), sin(turns));
+				glRotated(180+deg, 0, 0, 1);
+				draw_octahedron();
+			}
+		}
+
+		glfwSwapBuffers(window);
+		glfwPollEvents();
+	}
+	glfwTerminate(); /* Implicit window destroy */
+}