examples

commit 8968680f2b50176103d4422573d64478cf5994d4
parent c00d0b4d3c6d0a3eed86310c265f620c4a883264
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Fri, 22 Sep 2023 21:23:24 +0100

gl*: Small improvements

Diffstat:
M
Tupfile
 | 
2
+-
M
src/gl-3d.c
 | 
57
+++++++++++++++++++++++++++++++++++++++++++++++++++++++--
M
src/gl.c
 | 
6
+++++-
M
src/glob.c
 | 
8
+++++++-

4 files changed, 68 insertions(+), 5 deletions(-)
diff --git a/Tupfile b/Tupfile
@@ -5,7 +5,7 @@ CXXFLAGS = -std=c++20 $(COMMON_FLAGS)
 
 LDLIBS_aio = -lrt
 LDLIBS_alsa-simple = -lasound
-LDLIBS_gl = -lglfw -lGL
+LDLIBS_gl = -lglfw -lGL -lm
 LDLIBS_gl-3d = -lglfw -lGL -lm
 LDLIBS_gl-lighting = -lglfw -lGL -lm
 LDLIBS_gl-asteroids = -lglfw -lGL -lm -lasound
diff --git a/src/gl-3d.c b/src/gl-3d.c
@@ -38,6 +38,35 @@ static void draw_octahedron()
 	glDrawElements(GL_TRIANGLE_FAN, 6, GL_UNSIGNED_BYTE, octahedron_indices + 6);
 }
 
+float const duv = 1./32;
+
+struct vertex_t2v3
+{
+	float texcoord[2];
+	float vertex[3];
+} const plane_vertices[] =
+{
+	{{duv,duv}, {-.5,-.5,0.5}},
+	{{1-duv,duv}, { .5,-.5,0}},
+	{{duv,1-duv}, {-.5, .5,0}},
+	{{1-duv,1-duv}, { .5, .5,0}},
+};
+
+static void draw_plane()
+{
+
+	glEnable(GL_TEXTURE_2D);
+	glEnable(GL_POINT_SPRITE);
+	glColor3f(1,1,1);
+	
+	glInterleavedArrays(GL_V3F, sizeof(struct vertex_t2v3), plane_vertices->vertex);
+	glPointSize(64);
+	glTexEnvi(GL_POINT_SPRITE, GL_COORD_REPLACE, GL_TRUE);
+	glDrawArrays(GL_POINTS, 0, 4);
+	glDisable(GL_POINT_SPRITE);
+	glDisable(GL_TEXTURE_2D);
+}
+
 static void key_cb(GLFWwindow* w, int key, int /*scancode*/, int action, int /*mods*/)
 {
 	if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
@@ -63,8 +92,27 @@ static void fb_resize_cb(GLFWwindow*, int w, int h)
 	set_frustum_size(w, h);
 }
 
+static struct rgb {
+	unsigned char r,g,b;
+} tex[16*16*3];
+
 int main(int, char* argv[])
 {
+	struct rgb grey = {32,32,32};
+	for (unsigned i = 0; i < 16*16; ++i)
+	{
+		tex[i].r = i % 16 * 17;
+		tex[i].g = i / 16 * 17;
+		tex[i].b = 255-i;
+		tex[i] = grey;
+	};
+	struct rgb black = {0,0,0};
+	struct rgb green = {0,255,0};
+	for (unsigned i = 0; i < 16; ++i)
+	{
+		tex[i] = tex[15+i*16] = black;
+		tex[i*16] = tex[i+15*16] = green;
+	};
 	assert(glfwInit());
 	GLFWwindow* window = glfwCreateWindow(DEFAULT_W, DEFAULT_H, argv[0], NULL, NULL);
 	assert(window);
@@ -73,10 +121,15 @@ int main(int, char* argv[])
 	glfwSetKeyCallback(window, key_cb);
 	glfwSetFramebufferSizeCallback(window, fb_resize_cb);
 	glfwSwapInterval(1);
-	glClearColor(0, 0, 0, 1);
+	glClearColor(0.2, 0.2, 0.2, 1);
 	glEnable(GL_CULL_FACE);
 	glEnable(GL_DEPTH_TEST);
 
+	glTexImage2D(GL_TEXTURE_2D, 0, 3, 16, 16, 0, GL_RGB, GL_UNSIGNED_BYTE, tex);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+
 	while (!glfwWindowShouldClose(window))
 	{
 		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
@@ -114,7 +167,7 @@ int main(int, char* argv[])
 		{
 			glTranslated(sin(2*turns), cos(2*turns), sin(turns));
 			glRotated(180+deg, 0, 0, 1);
-			draw_octahedron();
+			draw_plane();
 		}
 
 		glfwSwapBuffers(window);
diff --git a/src/gl.c b/src/gl.c
@@ -2,6 +2,7 @@
 
 #include <GLFW/glfw3.h>
 #include <assert.h>
+#include <math.h>
 
 static void fb_resize_cb(GLFWwindow*, int w, int h)
 {
@@ -21,8 +22,11 @@ int main(int, char* argv[])
 	while (!glfwWindowShouldClose(window))
 	{
 		glfwPollEvents();
+		double t = glfwGetTime() / 2;
+		t = t - floor(t);
+		t *= 3;
 		glClear(GL_COLOR_BUFFER_BIT);
-		glRectd(-.5,-.5, .5, .5);
+		glRectd(t-2,-1, t-1, 1);
 		glfwSwapBuffers(window);
 	}
 	glfwTerminate(); /* Implicit window destroy */
diff --git a/src/glob.c b/src/glob.c
@@ -3,6 +3,12 @@
 #include <stdlib.h>
 #include <string.h>
 
+int errfunc(char const* epath, int eerrno)
+{
+	fprintf(stderr, "glob: %s %s\n", epath, strerror(eerrno));
+	return 0;
+}
+
 static int cmpstringp(const void *p1, const void *p2)
 {
    return strcmp(* (char * const *) p1, * (char * const *) p2);
@@ -18,7 +24,7 @@ int main(int argc, char* argv[])
 
     for (int i = 1; i < argc; ++i)
     {
-        glob(argv[i], flags, NULL, &results);
+        glob(argv[i], flags, errfunc, &results);
         flags |= GLOB_APPEND;
     }