opengl-learn

step-by-step introduction to OpenGL ES 2.0
git clone https://0xdd.org/code/opengl-learn.git
Log | Files | Refs | LICENSE

commit ddfb5806153cd123889e2900006d17eab3e4f870
parent dccf2b0738e933aa67110634812c9803c20b8010
Author: David DiPaola <DavidDiPaola@users.noreply.github.com>
Date:   Sat,  9 Jun 2018 20:55:32 -0400

00,01,02: made code more consistent so it can be diffed for easier learnings

Diffstat:
00-triangle.c | 41++++++++++++++++++-----------------------
01-perspective.c | 61++++++++++++++++++++++++++-----------------------------------
02-cube.c | 62++++++++++++++++++++++++++++----------------------------------
3 files changed, 72 insertions(+), 92 deletions(-)

diff --git a/00-triangle.c b/00-triangle.c @@ -26,40 +26,42 @@ main() { return status; } - const char * vertexshader = + const char * program_vertex_source = "#version 100" "\n" - "attribute vec4 position;" "\n" + "precision highp float;" "\n" + "attribute vec3 attribute_position;" "\n" /* attributes are inputs to vertex shaders */ "void main(){" "\n" - " gl_Position = position;" "\n" + " gl_Position = vec4(attribute_position,1);" "\n" "}" "\n" ; - const char * fragmentshader = + const char * program_fragment_source = "#version 100" "\n" + "precision lowp float;" "\n" "void main() {" "\n" " gl_FragColor = vec4(1,0,0,1);" "\n" "}" "\n" ; GLuint program_ID = 0; - status = ogl_program_build(vertexshader, fragmentshader, &program_ID); + status = ogl_program_build(program_vertex_source, program_fragment_source, &program_ID); if (status < 0) { fprintf(stderr, "\t" "at %s : %d" "\n", __FILE__, __LINE__); return status; } GLint program_attribute_position_ID = 0; - status = ogl_program_attribute_get_ID(program_ID, "position", &program_attribute_position_ID); + status = ogl_program_attribute_get_ID(program_ID, "attribute_position", &program_attribute_position_ID); if (status < 0) { fprintf(stderr, "\t" "at %s : %d" "\n", __FILE__, __LINE__); return status; } - static const GLfloat triangle_vertex_data[] = { - -1.0f, -1.0f, 0.0f, - 1.0f, -1.0f, 0.0f, - 0.0f, 1.0f, 0.0f, + const GLfloat triangle_vertexbuffer_data[] = { + -1.0f, -1.0f, 0.0f, 1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f, }; - GLuint triangle_vertex_buffer_ID = 0; - status = ogl_vertex_buffer_load(triangle_vertex_data, sizeof(triangle_vertex_data), &triangle_vertex_buffer_ID); + const size_t triangle_vertexbuffer_data_size = sizeof(triangle_vertexbuffer_data); + const size_t triangle_vertexbuffer_data_vertexes = (sizeof(triangle_vertexbuffer_data) / sizeof(*triangle_vertexbuffer_data)) / 3; + GLuint triangle_vertexbuffer_ID = 0; + status = ogl_vertex_buffer_load(triangle_vertexbuffer_data, triangle_vertexbuffer_data_size, &triangle_vertexbuffer_ID); if (status < 0) { return status; } @@ -70,16 +72,9 @@ main() { glUseProgram(program_ID); glEnableVertexAttribArray(program_attribute_position_ID); - glBindBuffer(GL_ARRAY_BUFFER, triangle_vertex_buffer_ID); - glVertexAttribPointer( - program_attribute_position_ID, // The attribute we want to configure - 3, // size - GL_FLOAT, // type - GL_FALSE, // is normalized? - 0, // stride - (GLvoid *)0 // array buffer offset - ); - glDrawArrays(GL_TRIANGLES, 0, 3); // 3 indices starting at 0 -> 1 triangle + glBindBuffer(GL_ARRAY_BUFFER, triangle_vertexbuffer_ID); + glVertexAttribPointer(program_attribute_position_ID, 3, GL_FLOAT, GL_FALSE, 0, (GLvoid *)0); + glDrawArrays(GL_TRIANGLES, 0, triangle_vertexbuffer_data_vertexes); glBindBuffer(GL_ARRAY_BUFFER, 0); glDisableVertexAttribArray(program_attribute_position_ID); @@ -92,7 +87,7 @@ main() { (glfwWindowShouldClose(window) == 0) ); - glDeleteBuffers(1, &triangle_vertex_buffer_ID); + glDeleteBuffers(1, &triangle_vertexbuffer_ID); glDeleteProgram(program_ID); glfwTerminate(); diff --git a/01-perspective.c b/01-perspective.c @@ -3,6 +3,8 @@ licensed under CC0 (public domain, see https://creativecommons.org/publicdomain/zero/1.0/) */ +/* followed this tutorial: http://www.opengl-tutorial.org/beginners-tutorials/tutorial-3-matrices/ */ + #include <stdio.h> #include <stdlib.h> @@ -24,32 +26,31 @@ main() { return status; } - const char * vertexshader = + const char * program_vertex_source = "#version 100" "\n" - "uniform mat4 MVP;" "\n" - "attribute vec4 position;" "\n" + "precision highp float;" "\n" + "uniform mat4 uniform_MVP;" "\n" /* uniforms are inputs to vertex shaders that don't change per-vertex */ + "attribute vec3 attribute_position;" "\n" /* attributes are inputs to vertex shaders */ "void main(){" "\n" - " gl_Position = MVP * position;" "\n" + " gl_Position = uniform_MVP * vec4(attribute_position,1);" "\n" "}" "\n" ; - const char * fragmentshader = + const char * program_fragment_source = "#version 100" "\n" + "precision lowp float;" "\n" "void main() {" "\n" " gl_FragColor = vec4(1,0,0,1);" "\n" "}" "\n" ; GLuint program_ID = 0; - status = ogl_program_build( - vertexshader, fragmentshader, - &program_ID - ); + status = ogl_program_build(program_vertex_source, program_fragment_source, &program_ID); if (status < 0) { fprintf(stderr, "\t" "at %s : %d" "\n", __FILE__, __LINE__); return status; } GLint program_attribute_position_ID = 0; - status = ogl_program_attribute_get_ID(program_ID, "position", &program_attribute_position_ID); + status = ogl_program_attribute_get_ID(program_ID, "attribute_position", &program_attribute_position_ID); if (status < 0) { fprintf(stderr, "\t" "at %s : %d" "\n", __FILE__, __LINE__); return status; @@ -63,13 +64,10 @@ main() { } struct ogl_mat4f MVP_view; - struct ogl_vec3f MVP_view_eye = { .x=4.0f, .y=3.0f, .z=3.0f }; - struct ogl_vec3f MVP_view_center = { .x=0.0f, .y=0.0f, .z=0.0f }; - struct ogl_vec3f MVP_view_up = { .x=0.0f, .y=1.0f, .z=0.0f }; - ogl_lookat( - MVP_view_eye, MVP_view_center, MVP_view_up, - &MVP_view - ); + struct ogl_vec3f MVP_view_eye = { .x= 4.0f, .y= 3.0f, .z= 3.0f }; + struct ogl_vec3f MVP_view_center = { .x= 0.0f, .y= 0.0f, .z= 0.0f }; + struct ogl_vec3f MVP_view_up = { .x= 0.0f, .y= 1.0f, .z= 0.0f }; + ogl_lookat(MVP_view_eye, MVP_view_center, MVP_view_up, &MVP_view); struct ogl_mat4f MVP_model; ogl_mat4f_identity(&MVP_model); @@ -80,13 +78,13 @@ main() { ogl_mat4f_multiply(MVP, MVP_view, &MVP); ogl_mat4f_multiply(MVP, MVP_model, &MVP); - static const GLfloat triangle_vertex_data[] = { - -1.0f, -1.0f, 0.0f, - 1.0f, -1.0f, 0.0f, - 0.0f, 1.0f, 0.0f, + const GLfloat triangle_vertexbuffer_data[] = { + -1.0f, -1.0f, 0.0f, 1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f, }; - GLuint triangle_vertex_buffer_ID = 0; - status = ogl_vertex_buffer_load(triangle_vertex_data, sizeof(triangle_vertex_data), &triangle_vertex_buffer_ID); + const size_t triangle_vertexbuffer_data_size = sizeof(triangle_vertexbuffer_data); + const size_t triangle_vertexbuffer_data_vertexes = (sizeof(triangle_vertexbuffer_data) / sizeof(*triangle_vertexbuffer_data)) / 3; + GLuint triangle_vertexbuffer_ID = 0; + status = ogl_vertex_buffer_load(triangle_vertexbuffer_data, triangle_vertexbuffer_data_size, &triangle_vertexbuffer_ID); if (status < 0) { return status; } @@ -95,19 +93,12 @@ main() { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glUseProgram(program_ID); - ogl_program_uniform_set_mat4f(program_ID, "MVP", MVP); + ogl_program_uniform_set_mat4f(program_ID, "uniform_MVP", MVP); glEnableVertexAttribArray(program_attribute_position_ID); - glBindBuffer(GL_ARRAY_BUFFER, triangle_vertex_buffer_ID); - glVertexAttribPointer( - program_attribute_position_ID, // The attribute we want to configure - 3, // size - GL_FLOAT, // type - GL_FALSE, // is normalized? - 0, // stride - (GLvoid *)0 // array buffer offset - ); - glDrawArrays(GL_TRIANGLES, 0, 3); // 3 indices starting at 0 -> 1 triangle + glBindBuffer(GL_ARRAY_BUFFER, triangle_vertexbuffer_ID); + glVertexAttribPointer(program_attribute_position_ID, 3, GL_FLOAT, GL_FALSE, 0, (GLvoid *)0); + glDrawArrays(GL_TRIANGLES, 0, triangle_vertexbuffer_data_vertexes); glBindBuffer(GL_ARRAY_BUFFER, 0); glDisableVertexAttribArray(program_attribute_position_ID); @@ -120,7 +111,7 @@ main() { (glfwWindowShouldClose(window) == 0) ); - glDeleteBuffers(1, &triangle_vertex_buffer_ID); + glDeleteBuffers(1, &triangle_vertexbuffer_ID); glDeleteProgram(program_ID); glfwTerminate(); diff --git a/02-cube.c b/02-cube.c @@ -3,6 +3,8 @@ licensed under CC0 (public domain, see https://creativecommons.org/publicdomain/zero/1.0/) */ +/* followed this tutorial: http://www.opengl-tutorial.org/beginners-tutorials/tutorial-4-a-colored-cube/ */ + #include <stdio.h> #include <stdlib.h> @@ -24,45 +26,42 @@ main() { return status; } - const char * vertexshader = + const char * program_vertex_source = "#version 100" "\n" "precision highp float;" "\n" - "attribute vec3 vertex_in_position;" "\n" - "attribute vec3 vertex_in_color;" "\n" - "varying vec4 vertex_out_fragment_in_color;" "\n" - "uniform mat4 MVP;" "\n" + "uniform mat4 uniform_MVP;" "\n" /* uniforms are inputs to vertex shaders that don't change per-vertex */ + "attribute vec3 attribute_position;" "\n" /* attributes are inputs to vertex shaders */ + "attribute vec3 attribute_color;" "\n" + "varying vec4 varying_color;" "\n" /* varyings are outputs of vertex shaders and inputs to fragment shaders */ "void main(){" "\n" - " gl_Position = MVP * vec4(vertex_in_position, 1);" "\n" - " vertex_out_fragment_in_color = vec4(vertex_in_color, 1);" "\n" + " gl_Position = uniform_MVP * vec4(attribute_position,1);" "\n" + " varying_color = vec4(attribute_color,1);" "\n" "}" "\n" ; - const char * fragmentshader = + const char * program_fragment_source = "#version 100" "\n" "precision lowp float;" "\n" - "varying vec4 vertex_out_fragment_in_color;" "\n" + "varying vec4 varying_color;" "\n" "void main() {" "\n" - " gl_FragColor = vertex_out_fragment_in_color;" "\n" + " gl_FragColor = varying_color;" "\n" "}" "\n" ; GLuint program_ID = 0; - status = ogl_program_build( - vertexshader, fragmentshader, - &program_ID - ); + status = ogl_program_build(program_vertex_source, program_fragment_source, &program_ID); if (status < 0) { fprintf(stderr, "\t" "at %s : %d" "\n", __FILE__, __LINE__); return status; } - GLint program_vertex_in_position_ID = 0; - status = ogl_program_attribute_get_ID(program_ID, "vertex_in_position", &program_vertex_in_position_ID); + GLint program_attribute_position_ID = 0; + status = ogl_program_attribute_get_ID(program_ID, "attribute_position", &program_attribute_position_ID); if (status < 0) { fprintf(stderr, "\t" "at %s : %d" "\n", __FILE__, __LINE__); return status; } - GLint program_vertex_in_color_ID = 0; - status = ogl_program_attribute_get_ID(program_ID, "vertex_in_color", &program_vertex_in_color_ID); + GLint program_attribute_color_ID = 0; + status = ogl_program_attribute_get_ID(program_ID, "attribute_color", &program_attribute_color_ID); if (status < 0) { fprintf(stderr, "\t" "at %s : %d" "\n", __FILE__, __LINE__); return status; @@ -79,10 +78,7 @@ main() { struct ogl_vec3f MVP_view_eye = { .x= 4.0f, .y= 3.0f, .z=-3.0f }; struct ogl_vec3f MVP_view_center = { .x= 0.0f, .y= 0.0f, .z= 0.0f }; struct ogl_vec3f MVP_view_up = { .x= 0.0f, .y= 1.0f, .z= 0.0f }; - ogl_lookat( - MVP_view_eye, MVP_view_center, MVP_view_up, - &MVP_view - ); + ogl_lookat(MVP_view_eye, MVP_view_center, MVP_view_up, &MVP_view); struct ogl_mat4f MVP_model; ogl_mat4f_identity(&MVP_model); @@ -107,9 +103,8 @@ main() { 1.0f, 1.0f, 1.0f, -1.0f, 1.0f,-1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f,-1.0f, 1.0f, }; - static const size_t cube_vertexbuffer_data_size = sizeof(cube_vertexbuffer_data); - static const size_t cube_vertexbuffer_data_triangles = (sizeof(cube_vertexbuffer_data) / sizeof(*cube_vertexbuffer_data)) / 3; - + static const size_t cube_vertexbuffer_data_size = sizeof(cube_vertexbuffer_data); + static const size_t cube_vertexbuffer_data_vertexes = (sizeof(cube_vertexbuffer_data) / sizeof(*cube_vertexbuffer_data)) / 3; GLuint cube_vertexbuffer_ID = 0; status = ogl_vertex_buffer_load(cube_vertexbuffer_data, cube_vertexbuffer_data_size, &cube_vertexbuffer_ID); if (status < 0) { @@ -131,7 +126,6 @@ main() { 0.673f,0.211f,0.457f, 0.820f,0.883f,0.371f, 0.982f,0.099f,0.879f, }; static const size_t cube_colorbuffer_data_size = sizeof(cube_colorbuffer_data); - GLuint cube_colorbuffer_ID = 0; status = ogl_vertex_buffer_load(cube_colorbuffer_data, cube_colorbuffer_data_size, &cube_colorbuffer_ID); if (status < 0) { @@ -142,21 +136,21 @@ main() { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glUseProgram(program_ID); - ogl_program_uniform_set_mat4f(program_ID, "MVP", MVP); + ogl_program_uniform_set_mat4f(program_ID, "uniform_MVP", MVP); - glEnableVertexAttribArray(program_vertex_in_position_ID); + glEnableVertexAttribArray(program_attribute_position_ID); glBindBuffer(GL_ARRAY_BUFFER, cube_vertexbuffer_ID); - glVertexAttribPointer(program_vertex_in_position_ID, 3, GL_FLOAT, GL_FALSE, 0, (GLvoid *)0); + glVertexAttribPointer(program_attribute_position_ID, 3, GL_FLOAT, GL_FALSE, 0, (GLvoid *)0); - glEnableVertexAttribArray(program_vertex_in_color_ID); + glEnableVertexAttribArray(program_attribute_color_ID); glBindBuffer(GL_ARRAY_BUFFER, cube_colorbuffer_ID); - glVertexAttribPointer(program_vertex_in_color_ID, 3, GL_FLOAT, GL_FALSE, 0, (GLvoid *)0); + glVertexAttribPointer(program_attribute_color_ID, 3, GL_FLOAT, GL_FALSE, 0, (GLvoid *)0); - glDrawArrays(GL_TRIANGLES, 0, cube_vertexbuffer_data_triangles); + glDrawArrays(GL_TRIANGLES, 0, cube_vertexbuffer_data_vertexes); glBindBuffer(GL_ARRAY_BUFFER, 0); - glDisableVertexAttribArray(program_vertex_in_position_ID); - glDisableVertexAttribArray(program_vertex_in_color_ID); + glDisableVertexAttribArray(program_attribute_position_ID); + glDisableVertexAttribArray(program_attribute_color_ID); glfwSwapBuffers(window); glfwPollEvents();