From a091c00c00c1d5ae5e3da7ef31b98293c76d479f Mon Sep 17 00:00:00 2001
From: pants <niklasjo2004@gmail.com>
Date: Mon, 21 Sep 2026 14:16:59 -0700
Subject: init

---
 src/shader.c | 147 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 147 insertions(+)
 create mode 100644 src/shader.c

(limited to 'src/shader.c')

diff --git a/src/shader.c b/src/shader.c
new file mode 100644
index 0000000..d952d5d
--- /dev/null
+++ b/src/shader.c
@@ -0,0 +1,147 @@
+#include "../include/shader.h"
+#include "../include/egl.h"
+#include <stdio.h>
+#include <assert.h>
+
+static bool print_compile_errors = false;
+
+static int min_int(int a, int b) {
+    return a < b ? a : b;
+}
+
+static unsigned int load_shader(gsr_egl *egl, unsigned int type, const char *source) {
+    unsigned int shader_id = egl->glCreateShader(type);
+    if(shader_id == 0) {
+        fprintf(stderr, "gsr error: load_shader: failed to create shader, error: %d\n", egl->glGetError());
+        return 0;
+    }
+
+    egl->glShaderSource(shader_id, 1, &source, NULL);
+    egl->glCompileShader(shader_id);
+
+    int compiled = 0;
+    egl->glGetShaderiv(shader_id, GL_COMPILE_STATUS, &compiled);
+    if(!compiled) {
+        int info_length = 0;
+        egl->glGetShaderiv(shader_id, GL_INFO_LOG_LENGTH, &info_length);
+        
+        if(info_length > 1 && print_compile_errors) {
+            char info_log[4096];
+            egl->glGetShaderInfoLog(shader_id, min_int(4096, info_length), NULL, info_log);
+            fprintf(stderr, "gsr error: load_shader: failed to compile shader, error:\n%s\nshader source:\n%s\n", info_log, source);
+        }
+
+        egl->glDeleteShader(shader_id);
+        return 0;
+    }
+
+    return shader_id;
+}
+
+static unsigned int load_program(gsr_egl *egl, const char *vertex_shader, const char *fragment_shader) {
+    unsigned int vertex_shader_id = 0;
+    unsigned int fragment_shader_id = 0;
+    unsigned int program_id = 0;
+    int linked = 0;
+    bool success = false;
+
+    if(vertex_shader) {
+        vertex_shader_id = load_shader(egl, GL_VERTEX_SHADER, vertex_shader);
+        if(vertex_shader_id == 0)
+            goto done;
+    }
+
+    if(fragment_shader) {
+        fragment_shader_id = load_shader(egl, GL_FRAGMENT_SHADER, fragment_shader);
+        if(fragment_shader_id == 0)
+            goto done;
+    }
+
+    program_id = egl->glCreateProgram();
+    if(program_id == 0) {
+        fprintf(stderr, "gsr error: load_program: failed to create shader program, error: %d\n", egl->glGetError());
+        goto done;
+    }
+
+    if(vertex_shader_id)
+        egl->glAttachShader(program_id, vertex_shader_id);
+
+    if(fragment_shader_id)
+        egl->glAttachShader(program_id, fragment_shader_id);
+
+    egl->glLinkProgram(program_id);
+
+    egl->glGetProgramiv(program_id, GL_LINK_STATUS, &linked);
+    if(!linked) {
+        int info_length = 0;
+        egl->glGetProgramiv(program_id, GL_INFO_LOG_LENGTH, &info_length);
+        
+        if(info_length > 1) {
+            char info_log[4096];
+            egl->glGetProgramInfoLog(program_id, min_int(4096, info_length), NULL, info_log);
+            fprintf(stderr, "gsr error: load program: linking shader program failed, error:\n%s\n", info_log);            
+        }
+
+        goto done;
+    }
+
+    success = true;
+    done:
+
+    if(!success) {
+        if(program_id)
+            egl->glDeleteProgram(program_id);
+    }
+    if(fragment_shader_id)
+        egl->glDeleteShader(fragment_shader_id);
+    if(vertex_shader_id)
+        egl->glDeleteShader(vertex_shader_id);
+    return program_id;
+}
+
+int gsr_shader_init(gsr_shader *self, gsr_egl *egl, const char *vertex_shader, const char *fragment_shader) {
+    assert(egl);
+    self->egl = egl;
+    self->program_id = 0;
+
+    if(!vertex_shader && !fragment_shader) {
+        fprintf(stderr, "gsr error: gsr_shader_init: vertex and fragment shader can't be NULL at the same time\n");
+        return -1;
+    }
+
+    self->program_id = load_program(self->egl, vertex_shader, fragment_shader);
+    if(self->program_id == 0)
+        return -1;
+
+    return 0;
+}
+
+void gsr_shader_deinit(gsr_shader *self) {
+    if(!self->egl)
+        return;
+
+    if(self->program_id) {
+        self->egl->glDeleteProgram(self->program_id);
+        self->program_id = 0;
+    }
+
+    self->egl = NULL;
+}
+
+int gsr_shader_bind_attribute_location(gsr_shader *self, const char *attribute, int location) {
+    while(self->egl->glGetError()) {}
+    self->egl->glBindAttribLocation(self->program_id, location, attribute);
+    return self->egl->glGetError();
+}
+
+void gsr_shader_use(gsr_shader *self) {
+    self->egl->glUseProgram(self->program_id);
+}
+
+void gsr_shader_use_none(gsr_shader *self) {
+    self->egl->glUseProgram(0);
+}
+
+void gsr_shader_enable_debug_output(bool enable) {
+    print_compile_errors = enable;
+}
-- 
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