GTK4_GG_hack/draw.c.todo

/*
 *      Gem-graph OpenGL experiments
 *
 *      Desc: GL functions
 *
 *  Copyright (C) 2023 Adrien Bourmault <neox@a-lec.org>
 *  Copyright (C) 2023 Jean Sirmai <jean@a-lec.org>
 *
 *  This file is part of Gem-graph.
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *  Writes values to describe a vertex at (x,y,z) intoq the vertex buffer
 *
 *  @param coords GLfloat(x,y,z)
 *
 *  @return void
 */

#include <stdlib.h>
#include <time.h>
#include <cglm/cglm.h>
#include "base.h"
//#include "ui.h"
#include "graph_area.h"

void graphics_draw_vertex (const int stack_id,
                           GLfloat x,
                           GLfloat y,
                           GLfloat z)
{
    //g_printerr("stack_id is %d\n", stack_id);
    //g_printerr("stack_id is %d\n", stack_id);
    //g_printerr("graphic_stack is at %p\n", graphic_stack);
    //g_printerr("graphic_stack[stack_id] is at %p\n", graphic_stack + stack_id);
    volatile struct graphic_stack_t *stack = &graphic_stack[stack_id];

    //g_printerr("Currently stack->buffer_vertex_origin @ %p\n", stack->buffer_vertex_origin);

    //assert (stack->buffer_vertex_origin);

    stack->buffer_vertex_origin =
            g_realloc (stack->buffer_vertex_origin,
                       (stack->buffer_vertex_size + 3) * sizeof(GLfloat));
    //print_stack(stack_id);

    stack->buffer_vertex_origin[stack->buffer_vertex_size + 0] = x;
    stack->buffer_vertex_origin[stack->buffer_vertex_size + 1] = y;
    stack->buffer_vertex_origin[stack->buffer_vertex_size + 2] = z;

    stack->buffer_vertex_size += 3;
}

/*
 *  Writes values to describe a color (r,g,b) into the color buffer
 *
 *  @param color GLfloat(r,g,b)
 *
 *  @return void
 */
void graphics_draw_color (const int stack_id,
                          GLfloat r,
                          GLfloat g,
                          GLfloat b)
{
    struct graphic_stack_t *stack = &graphic_stack[stack_id];

    stack->buffer_colors_origin = g_realloc (stack->buffer_colors_origin,
                                     (stack->buffer_colors_size + 3) * sizeof(GLfloat));

    assert (stack->buffer_colors_origin);

    stack->buffer_colors_origin[stack->buffer_colors_size + 0] = r;
    stack->buffer_colors_origin[stack->buffer_colors_size + 1] = g;
    stack->buffer_colors_origin[stack->buffer_colors_size + 2] = b;

    stack->buffer_colors_size += 3;
}

/*
 *  Writes values to describe a line from a to b into the line buffer
 *
 *  @param coords GLuint (a,b)
 *
 *  @return void
 */
void graphics_draw_line (const int stack_id,
                         GLuint a,
                         GLuint b)
{
    struct graphic_stack_t *stack = &graphic_stack[stack_id];

    stack->buffer_lines_origin = g_realloc (stack->buffer_lines_origin,
                                    (stack->buffer_lines_size + 2) * sizeof(GLuint));

    assert (stack->buffer_lines_origin);

    stack->buffer_lines_origin[stack->buffer_lines_size + 0] = a;
    stack->buffer_lines_origin[stack->buffer_lines_size + 1] = b;

    stack->buffer_lines_size += 2;
}

/*
 *  Writes values to describe an (a,b,c) plan (triangle) into the plan buffer
 *
 *  @param coords GLuint (a,b,c)
 *
 *  @return void
 */
void graphics_draw_plan (const int stack_id,
                         GLuint a,
                         GLuint b,
                         GLuint c)
{
    struct graphic_stack_t *stack = &graphic_stack[stack_id];

    stack->buffer_plans_origin = g_realloc (stack->buffer_plans_origin,
                                    (stack->buffer_plans_size + 3) * sizeof(GLuint));

    assert (stack->buffer_plans_origin);

    stack->buffer_plans_origin[stack->buffer_plans_size + 0] = a;
    stack->buffer_plans_origin[stack->buffer_plans_size + 1] = b;
    stack->buffer_plans_origin[stack->buffer_plans_size + 2] = c;

    stack->buffer_plans_size += 3;
}

/*
 * Draws the current buffer to a gl_area
 *
 * @param   gl_area, ptr to the gl_area widget
 *
 * @return  void
 */
void graphics_draw(const int stack_id)
{
    struct graphic_stack_t *stack = &graphic_stack[stack_id];

    //g_printerr("[debug] graphics_draw() started\n");

    //print_stack(stack_id);

    GLint cur_viewport[4];
    glGetIntegerv(GL_VIEWPORT, cur_viewport);

    mat4 m = GLM_MAT4_IDENTITY_INIT;
    glm_rotate_x(m, glm_rad(stack->rotation_angles[X_AXIS]), m);
    glm_rotate_y(m, glm_rad(stack->rotation_angles[Y_AXIS]), m);
    glm_rotate_z(m, glm_rad(stack->rotation_angles[Z_AXIS]), m);

    mat4 v = GLM_MAT4_IDENTITY_INIT; // XXX define zoom and translations here ?

    mat4 p = GLM_MAT4_IDENTITY_INIT;
    //glm_ortho(-1.0f, +1.0f, -1.0f, +1.0f, -1.0f, +1.0f, p);
    glm_ortho_default((float)cur_viewport[2] / (float)cur_viewport[3], p);
    //glm_perspective_default((float)cur_viewport[2] / (float)cur_viewport[3], p);

    /* Use our shaders */
    glUseProgram(stack->program);

    glClearColor(0, 0, 0, 1);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    /* Update the "mvp" matrix we use in the shader */
    glUniformMatrix4fv(stack->m, 1, GL_FALSE, (float *)m);
    glUniformMatrix4fv(stack->v, 1, GL_FALSE, (float *)v);
    glUniformMatrix4fv(stack->p, 1, GL_FALSE, (float *)p);

    /* Use the vertices in our buffer */
    glEnableVertexAttribArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, stack->position_buffer);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0,(void*)0);

    // couleurs
    glEnableVertexAttribArray(1);
    glBindBuffer(GL_ARRAY_BUFFER, stack->color_buffer);
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 0,(void*)0);

    //glEnable(GL_DEPTH_TEST);

    glDrawElements(GL_LINES, stack->buffer_lines_size, GL_UNSIGNED_INT, stack->buffer_lines_origin);
    glDrawElements(GL_TRIANGLES, stack->buffer_plans_size, GL_UNSIGNED_INT, stack->buffer_plans_origin);

    /* We finished using the buffers and program */
    glDisableVertexAttribArray(0);
    glDisableVertexAttribArray(1);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glUseProgram(0);

    glFlush();
    //g_printerr("[debug] graphics_draw() ended\n");
}