From 6b65556ef11e9acf79bbecdac8d205a973d5dc9b Mon Sep 17 00:00:00 2001
From: Tomasz Kramkowski <tk@the-tk.com>
Date: Tue, 27 Mar 2018 19:06:07 +0100
Subject: Add more vertex attributes (use a struct)

---
 frag.glsl |  3 ++-
 gltest.c  | 21 +++++++++++++++------
 nelem.h   |  6 ++++++
 vert.glsl |  5 +++++
 4 files changed, 28 insertions(+), 7 deletions(-)
 create mode 100644 nelem.h

diff --git a/frag.glsl b/frag.glsl
index aa5ec0f..c48ee57 100644
--- a/frag.glsl
+++ b/frag.glsl
@@ -2,8 +2,9 @@
 // SPDX-License-Identifier: MIT
 #version 330 core
 out vec4 color;
+in vec3 vcolor;
 
 void main()
 {
-	color = vec4(1.0f, 0.5f, 0.2f, 1.0f);
+	color = vec4(vcolor, 1.0);
 }
diff --git a/gltest.c b/gltest.c
index cb43383..5b1d4fc 100644
--- a/gltest.c
+++ b/gltest.c
@@ -11,6 +11,7 @@
 #include "linmath.h"
 #include "loadgl.h"
 #include "shaders.h"
+#include "nelem.h"
 
 enum {
 	WIDTH = 800,
@@ -35,11 +36,15 @@ int main(int argc, char **argv)
 	int ret;
 	GLuint ebo, vbo, vao, prog;
 	GLint ucolor;
-	vec3 verts[] = {
-		{  0.5f,  0.5f, 0.0f },
-		{  0.5f, -0.5f, 0.0f },
-		{ -0.5f, -0.5f, 0.0f },
-		{ -0.5f,  0.5f, 0.0f },
+	struct vertex {
+		vec3 pos;
+		vec3 col;
+		vec2 uv;
+	} verts[] = {
+		{{  0.5,  0.5, 0.0 }, { 1.0, 0.0, 0.0 }, { 1.0, 1.0 }},
+		{{  0.5, -0.5, 0.0 }, { 0.0, 1.0, 0.0 }, { 1.0, 0.0 }},
+		{{ -0.5, -0.5, 0.0 }, { 0.0, 0.0, 1.0 }, { 0.0, 0.0 }},
+		{{ -0.5,  0.5, 0.0 }, { 1.0, 1.0, 0.0 }, { 0.0, 1.0 }},
 	};
 	GLuint idxs[] = {
 		0, 1, 3,
@@ -77,8 +82,12 @@ int main(int argc, char **argv)
 	gl_buf_bind(GL_ELEMENT_ARRAY_BUFFER, ebo);
 	gl_buf_data(GL_ELEMENT_ARRAY_BUFFER, sizeof idxs, idxs, GL_STATIC_DRAW);
 
-	gl_va_define(0, 3, GL_FLOAT, GL_FALSE, sizeof *verts, 0);
+	gl_va_define(0, NELEM(verts[0].pos), GL_FLOAT, GL_FALSE, sizeof *verts, (void *)offsetof(struct vertex, pos));
 	gl_va_enable(0);
+	gl_va_define(1, NELEM(verts[0].col), GL_FLOAT, GL_FALSE, sizeof *verts, (void *)offsetof(struct vertex, col));
+	gl_va_enable(1);
+	gl_va_define(2, NELEM(verts[0].uv), GL_FLOAT, GL_FALSE, sizeof *verts, (void *)offsetof(struct vertex, uv));
+	gl_va_enable(2);
 
 	prog = glprog_load(2, (struct shdrdat []){
 			{ GL_VERTEX_SHADER, shader_vert_data, shader_vert_size },
diff --git a/nelem.h b/nelem.h
new file mode 100644
index 0000000..4d9b96e
--- /dev/null
+++ b/nelem.h
@@ -0,0 +1,6 @@
+#ifndef NELEM_H
+#define NELEM_H
+
+#define NELEM(a) (sizeof (a) / sizeof (a)[0])
+
+#endif // NELEM_H
diff --git a/vert.glsl b/vert.glsl
index 1730d35..2ee78d0 100644
--- a/vert.glsl
+++ b/vert.glsl
@@ -2,8 +2,13 @@
 // SPDX-License-Identifier: MIT
 #version 330 core
 layout (location = 0) in vec3 pos;
+layout (location = 1) in vec3 color;
+layout (location = 2) in vec2 uv;
+
+out vec3 vcolor;
 
 void main()
 {
 	gl_Position = vec4(pos, 1.0);
+	vcolor = color;
 }
-- 
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