From 68081ef4f1f51b5753e25a1be6f870eb2e84f76e Mon Sep 17 00:00:00 2001
From: lonkaars <loek@pipeframe.xyz>
Date: Thu, 16 May 2024 19:31:31 +0200
Subject: experiment with vertex shader

---
 fill.vert    | 10 ++++++++++
 hello.frag   |  8 --------
 hello.vert   |  7 -------
 main.c       | 12 ++++++------
 makefile     |  8 ++++----
 visuals.frag |  8 ++++++++
 6 files changed, 28 insertions(+), 25 deletions(-)
 create mode 100644 fill.vert
 delete mode 100644 hello.frag
 delete mode 100644 hello.vert
 create mode 100644 visuals.frag

diff --git a/fill.vert b/fill.vert
new file mode 100644
index 0000000..5633fd5
--- /dev/null
+++ b/fill.vert
@@ -0,0 +1,10 @@
+#version 330 core
+layout (location = 0) in vec3 vert;
+
+void main() {
+	// Setting w to 0 has the effect of an infinitely large zoom, which makes the
+	// single triangle fill the viewport completely. This is okay since I only
+	// care about the fragment shader.
+	gl_Position = vec4(vert.xyz, 0.0);
+}
+
diff --git a/hello.frag b/hello.frag
deleted file mode 100644
index 3539bdc..0000000
--- a/hello.frag
+++ /dev/null
@@ -1,8 +0,0 @@
-#version 330 core
-
-#include "config.h"
-
-void main() {
-	gl_FragColor = vec4(gl_FragCoord.x / WIDTH, gl_FragCoord.y / HEIGHT, 0, 1);
-}
-
diff --git a/hello.vert b/hello.vert
deleted file mode 100644
index 4af0bdf..0000000
--- a/hello.vert
+++ /dev/null
@@ -1,7 +0,0 @@
-#version 330 core
-layout (location = 0) in vec3 aPos;
-
-void main() {
-	gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);
-}
-
diff --git a/main.c b/main.c
index 0ff0706..09cf2fb 100644
--- a/main.c
+++ b/main.c
@@ -6,14 +6,14 @@
 #include "die.h"
 #include "config.h"
 
-#include "hello_vert.h"
-#include "hello_frag.h"
+#include "fill_vert.h"
+#include "visuals_frag.h"
 
 void prepare_tri() {
 	const float vertices[] = {
+		0, 1, 0,
+		1, -1, 0,
 		-1, -1, 0,
-		3, -1, 0,
-		-1, 3, 0,
 	};
 
 	// initialize vertex {buffer,attribute} object buffers
@@ -59,8 +59,8 @@ int main(int argc, char** argv) {
 
 	// prepare shaders
 	GLuint shader = link_shaders(
-		vert_shader(hello_vert, hello_vert_size),
-		frag_shader(hello_frag, hello_frag_size)
+		vert_shader(fill_vert, fill_vert_size),
+		frag_shader(visuals_frag, visuals_frag_size)
 	);
 
 	// main draw loop
diff --git a/makefile b/makefile
index 34c19bf..fa39ee9 100644
--- a/makefile
+++ b/makefile
@@ -12,12 +12,12 @@ all: main FORCE
 main: main.o
 main: die.o
 main: shader.o
-main: hello_frag.o
-main: hello_vert.o
+main: visuals_frag.o
+main: fill_vert.o
 
 # fix compile order
-main.o: hello_vert.h
-main.o: hello_frag.h
+main.o: fill_vert.h
+main.o: visuals_frag.h
 
 %.s %.h &: %.spv
 	./blob $< $*
diff --git a/visuals.frag b/visuals.frag
new file mode 100644
index 0000000..3539bdc
--- /dev/null
+++ b/visuals.frag
@@ -0,0 +1,8 @@
+#version 330 core
+
+#include "config.h"
+
+void main() {
+	gl_FragColor = vec4(gl_FragCoord.x / WIDTH, gl_FragCoord.y / HEIGHT, 0, 1);
+}
+
-- 
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