Add plugin support (-p option)

2 files changed, 158 insertions, 0 deletions

diff --git a/plugin/examples/hello_triangle/triangle.c b/plugin/examples/hello_triangle/triangle.c
new file mode 100644
index 0000000..4c18f20
--- /dev/null
+++ b/plugin/examples/hello_triangle/triangle.c
@@ -0,0 +1,108 @@
+#include <gsr/plugin.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <math.h>
+#define GL_GLEXT_PROTOTYPES
+#include <GL/gl.h>
+
+const char vertex_shader_source[] =
+    "attribute vec4 vertex_pos;   \n"
+    "void main() {                \n"
+    "   gl_Position = vertex_pos; \n"
+    "}";
+
+const char fragment_shader_source[] =
+    "precision mediump float;                    \n"
+    "uniform vec3 color;                         \n"
+    "void main() {                               \n"
+    "   gl_FragColor = vec4(color, 1.0); \n"
+    "}";
+
+typedef struct {
+    GLuint shader_program;
+    GLuint vao;
+    GLuint vbo;
+    GLint color_uniform;
+    unsigned int counter;
+} Triangle;
+
+static GLuint load_shader(const char *shaderSrc, GLenum type) {
+    GLuint shader = glCreateShader(type);
+    glShaderSource(shader, 1, &shaderSrc, NULL);
+    glCompileShader(shader);
+    return shader;
+}
+
+static void draw(const gsr_plugin_draw_params *params, void *userdata) {
+    Triangle *triangle = userdata;
+
+    GLfloat glverts[6];
+
+    glverts[0] = -0.5f;
+    glverts[1] = -0.5f;
+
+    glverts[2] = 0.5f;
+    glverts[3] = -0.5f;
+
+    glverts[4] = 0.0f;
+    glverts[5] = 0.5f;
+
+    glBindVertexArray(triangle->vao);
+    glBindBuffer(GL_ARRAY_BUFFER, triangle->vbo);
+    glBufferSubData(GL_ARRAY_BUFFER, 0, 6 * sizeof(float), glverts);
+
+    glUseProgram(triangle->shader_program);
+    const double pp = triangle->counter * 0.05;
+    glUniform3f(triangle->color_uniform, 0.5 + sin(pp)*0.5, 0.5 + cos(pp)*0.5, 0.5 + sin(0.2 + pp)*0.5);
+    glDrawArrays(GL_TRIANGLES, 0, 3);
+
+    glBindVertexArray(0);
+    glUseProgram(0);
+
+    ++triangle->counter;
+}
+
+bool gsr_plugin_init(const gsr_plugin_init_params *params, gsr_plugin_init_return *ret) {
+    Triangle *triangle = calloc(1, sizeof(Triangle));
+    if(!triangle)
+        return false;
+
+    triangle->shader_program = glCreateProgram();
+
+    const GLuint vertex_shader = load_shader(vertex_shader_source, GL_VERTEX_SHADER);
+    const GLuint fragment_shader = load_shader(fragment_shader_source, GL_FRAGMENT_SHADER);
+
+    glAttachShader(triangle->shader_program, vertex_shader);
+    glAttachShader(triangle->shader_program, fragment_shader);
+    glBindAttribLocation(triangle->shader_program, 0, "vertex_pos");
+    glLinkProgram(triangle->shader_program);
+
+    glGenVertexArrays(1, &triangle->vao);
+    glBindVertexArray(triangle->vao);
+
+    glGenBuffers(1, &triangle->vbo);
+    glBindBuffer(GL_ARRAY_BUFFER, triangle->vbo);
+    glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), NULL, GL_DYNAMIC_DRAW);
+
+    glEnableVertexAttribArray(0);
+    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (void *)0);
+
+    glBindVertexArray(0);
+
+    glDeleteShader(vertex_shader);
+    glDeleteShader(fragment_shader);
+
+    triangle->color_uniform = glGetUniformLocation(triangle->shader_program, "color");
+
+    ret->name = "hello_triangle";
+    ret->version = 1;
+    ret->userdata = triangle;
+    ret->draw = draw;
+    return true;
+}
+
+void gsr_plugin_deinit(void *userdata) {
+    Triangle *triangle = userdata;
+    glDeleteProgram(triangle->shader_program);
+    free(triangle);
+}
diff --git a/plugin/plugin.h b/plugin/plugin.h
new file mode 100644
index 0000000..bbf212d
--- /dev/null
+++ b/plugin/plugin.h
@@ -0,0 +1,50 @@
+#ifndef GSR_PLUGIN_H
+#define GSR_PLUGIN_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdbool.h>
+
+typedef enum {
+    GSR_PLUGIN_GRAPHICS_API_EGL_ES,
+    GSR_PLUGIN_GRAPHICS_API_GLX,
+} gsr_plugin_graphics_api;
+
+typedef enum {
+    GSR_PLUGIN_COLOR_DEPTH_8_BITS,
+    GSR_PLUGIN_COLOR_DEPTH_10_BITS,
+} gsr_plugin_color_depth;
+
+typedef struct {
+    unsigned int width;
+    unsigned int height;
+} gsr_plugin_draw_params;
+
+typedef struct {
+    unsigned int width;
+    unsigned int height;
+    unsigned int fps;
+    gsr_plugin_color_depth color_depth;
+    gsr_plugin_graphics_api graphics_api;
+} gsr_plugin_init_params;
+
+typedef struct {
+    const char *name; /* Mandatory */
+    unsigned int version; /* Mandatory, can't be 0 */
+    void *userdata; /* Optional */
+
+    /* Optional, called when the plugin is expected to draw something to the current framebuffer */
+    void (*draw)(const gsr_plugin_draw_params *params, void *userdata);
+} gsr_plugin_init_return;
+
+/* The plugin is expected to implement these functions and export them: */
+bool gsr_plugin_init(const gsr_plugin_init_params *params, gsr_plugin_init_return *ret);
+void gsr_plugin_deinit(void *userdata);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GSR_PLUGIN_H */