Add shader

1 files changed, 195 insertions, 0 deletions

diff --git a/src/graphics/shader.c b/src/graphics/shader.c
new file mode 100644
index 0000000..3d8a204
--- /dev/null
+++ b/src/graphics/shader.c
@@ -0,0 +1,195 @@
+#include "../../include/mgl/graphics/shader.h"
+#include "../../include/mgl/graphics/texture.h"
+#include "../../include/mgl/system/fileutils.h"
+#include "../../include/mgl/mgl.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+typedef struct {
+    unsigned int id;
+    mgl_shader_type shader_type;
+} mgl_shader;
+
+static unsigned int mgl_shader_type_to_gl_shader_type(mgl_shader_type shader_type) {
+    switch(shader_type) {
+        case MGL_SHADER_VERTEX:    return GL_VERTEX_SHADER;
+        case MGL_SHADER_FRAGMENT:  return GL_FRAGMENT_SHADER;
+        case MGL_SHADER_GEOMETRY:  return GL_GEOMETRY_SHADER;
+    }
+    return 0;
+}
+
+static void print_compile_log(mgl_context *context, unsigned int shader_id, const char *prefix) {
+    int log_length = 0;
+    context->gl.glGetShaderiv(shader_id, GL_INFO_LOG_LENGTH, &log_length);
+    if(log_length > 0) {
+        char *log_str = malloc(log_length + 1);
+        if(!log_str) {
+            fprintf(stderr, "Error: failed to allocate memory for shader compile log\n");
+            return;
+        }
+
+        log_str[0] = '\0';
+        log_str[log_length] = '\0';
+        context->gl.glGetShaderInfoLog(shader_id, log_length, NULL, log_str);
+
+        fprintf(stderr, "%s: %s\n", prefix, log_str);
+        free(log_str);
+    }
+}
+
+static void mgl_shader_unload(mgl_shader *self);
+
+static int mgl_shader_load_from_memory(mgl_shader *self, unsigned char *shader_data, int shader_size, mgl_shader_type shader_type) {
+    self->id = 0;
+    self->shader_type = shader_type;
+
+    mgl_context *context = mgl_get_context();
+    self->id = context->gl.glCreateShader(mgl_shader_type_to_gl_shader_type(shader_type));
+    if(self->id == 0) {
+        fprintf(stderr, "Error: failed to load shader, error: glCreateShader failed\n");
+        return -1;
+    }
+
+    context->gl.glShaderSource(self->id, 1, (const char* const*)&shader_data, &shader_size);
+    context->gl.glCompileShader(self->id);
+
+    int compiled_successfully = GL_FALSE;
+    context->gl.glGetShaderiv(self->id, GL_COMPILE_STATUS, &compiled_successfully);
+    if(compiled_successfully == GL_FALSE) {
+        print_compile_log(context, self->id, "Error");
+        mgl_shader_unload(self);
+        return -1;
+    }
+
+    print_compile_log(context, self->id, "Warning");
+    return 0;
+}
+
+static int mgl_shader_load_from_file(mgl_shader *self, const char *filepath, mgl_shader_type shader_type) {
+    self->id = 0;
+    self->shader_type = shader_type;
+
+    mgl_filedata filedata;
+    if(mgl_load_file(filepath, &filedata) != 0) {
+        fprintf(stderr, "Error: failed to load shader %s, error: mgl_load_file failed\n", filepath);
+        return -1;
+    }
+
+    if(filedata.size > INT32_MAX) {
+        fprintf(stderr, "Error: failed to load shader %s, error: shader size is too large\n", filepath);
+        return -1;
+    }
+
+    int res = mgl_shader_load_from_memory(self, filedata.data, filedata.size, shader_type);
+    mgl_filedata_free(&filedata);
+    return res;
+}
+
+void mgl_shader_unload(mgl_shader *self) {
+    mgl_context *context = mgl_get_context();
+    if(self->id) {
+        context->gl.glDeleteShader(self->id);
+        self->id = 0;
+    }
+}
+
+int mgl_shader_program_init(mgl_shader_program *self) {
+    self->id = 0;
+
+    mgl_context *context = mgl_get_context();
+    self->id = context->gl.glCreateProgram();
+    if(self->id == 0) {
+        fprintf(stderr, "Error: failed to create shader program: error glCreateProgram failed\n");
+        return -1;
+    }
+
+    return 0;
+}
+
+void mgl_shader_program_deinit(mgl_shader_program *self){
+    mgl_context *context = mgl_get_context();
+    if(self->id) {
+        context->gl.glDeleteProgram(self->id);
+        self->id = 0;
+    }
+}
+
+/* TODO: Check for attach shader error */
+
+int mgl_shader_program_add_shader_from_file(mgl_shader_program *self, const char *filepath, mgl_shader_type shader_type){
+    mgl_shader shader;
+    if(mgl_shader_load_from_file(&shader, filepath, shader_type) != 0)
+        return -1;
+
+    mgl_get_context()->gl.glAttachShader(self->id, shader.id);
+    mgl_shader_unload(&shader); /* TODO: Verify if deleting the shader here is always ok now that we have attached it */
+    return 0;
+}
+
+int mgl_shader_program_add_shader_from_memory(mgl_shader_program *self, unsigned char *shader_data, int shader_size, mgl_shader_type shader_type){
+    mgl_shader shader;
+    if(mgl_shader_load_from_memory(&shader, shader_data, shader_size, shader_type) != 0)
+        return -1;
+
+    mgl_get_context()->gl.glAttachShader(self->id, shader.id);
+    mgl_shader_unload(&shader); /* TODO: Verify if deleting the shader here is always ok now that we have attached it */
+    return 0;
+}
+
+static void print_link_log(mgl_context *context, unsigned int shader_id, const char *prefix) {
+    int log_length = 0;
+    context->gl.glGetProgramiv(shader_id, GL_INFO_LOG_LENGTH, &log_length);
+    if(log_length > 0) {
+        char *log_str = malloc(log_length + 1);
+        if(!log_str) {
+            fprintf(stderr, "Error: failed to allocate memory for shader link log\n");
+            return;
+        }
+
+        log_str[0] = '\0';
+        log_str[log_length] = '\0';
+        context->gl.glGetProgramInfoLog(shader_id, log_length, NULL, log_str);
+
+        fprintf(stderr, "%s: %s\n", prefix, log_str);
+        free(log_str);
+    }
+}
+
+int mgl_shader_program_finalize(mgl_shader_program *self) {
+    mgl_context *context = mgl_get_context();
+
+    context->gl.glLinkProgram(self->id);
+    int is_linked = GL_TRUE;
+    context->gl.glGetProgramiv(self->id, GL_LINK_STATUS, &is_linked);
+    if(is_linked == GL_FALSE) {
+        print_link_log(context, self->id, "Error");
+        return -1;
+    }
+
+    print_link_log(context, self->id, "Warning");
+    return 0;
+}
+
+/* TODO: Optimize glUseProgram */
+/* TODO: Optimize glGetUniformLocation */
+
+int mgl_shader_program_set_uniform_vec2f(mgl_shader_program *self, const char *uniform_name, mgl_vec2f value) {
+    mgl_context *context = mgl_get_context();
+    int uniform_location = context->gl.glGetUniformLocation(self->id, uniform_name);
+    if(uniform_location == -1) {
+        fprintf(stderr, "Error: no uniform by the name %s was found in the shader\n", uniform_name);
+        return -1;
+    }
+
+    context->gl.glUseProgram(self->id);
+    context->gl.glUniform2fv(uniform_location, 1, &value.x);
+    context->gl.glUseProgram(0);
+    return 0;
+}
+
+/* TODO: Optimize glUseProgram */
+void mgl_shader_program_use(mgl_shader_program *shader_program) {
+    mgl_context *context = mgl_get_context();
+    context->gl.glUseProgram(shader_program ? shader_program->id : 0);
+}