portersky
91fe3c6e8c
Each of the 6 cube-to-sphere faces now has a distinct color (red, green, blue, yellow, magenta, cyan) passed via a vertex color attribute. The fragment shader multiplies lighting by this color instead of a uniform blue. This makes the cube-face seams clearly visible when inspecting the mapped sphere.
215 lines
7.1 KiB
C++
215 lines
7.1 KiB
C++
#include <cstddef>
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#include <cmath>
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#include <vector>
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#include "glad/glad.h"
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#include "glm/gtc/matrix_transform.hpp"
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#include "glm/gtc/type_ptr.hpp"
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#include "scenes/sphere.hpp"
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namespace cbt::scenes {
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sphere::sphere() {
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m_start = std::chrono::steady_clock::now();
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}
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auto sphere::init() -> bool {
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if (!build_shader()) {
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return false;
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}
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build_mesh();
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glEnable(GL_DEPTH_TEST);
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return true;
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}
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auto sphere::update(float) -> void {}
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auto sphere::render() -> void {
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auto now = std::chrono::steady_clock::now();
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auto elapsed = std::chrono::duration<float>(now - m_start).count();
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glClearColor(0.15f, 0.15f, 0.2f, 1.0f);
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glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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auto aspect = 1280.0f / 720.0f;
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auto proj = glm::perspective(glm::radians(45.0f), aspect, 0.1f, 100.0f);
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auto view = glm::translate(glm::mat4{1.0f}, glm::vec3{0.0f, 0.0f, -4.0f});
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auto model = glm::rotate(glm::mat4{1.0f}, elapsed, glm::vec3{1.0f, 0.3f, 0.2f});
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m_prog.use();
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glUniformMatrix4fv(m_loc_proj, 1, GL_FALSE, glm::value_ptr(proj));
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glUniformMatrix4fv(m_loc_view, 1, GL_FALSE, glm::value_ptr(view));
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glUniformMatrix4fv(m_loc_model, 1, GL_FALSE, glm::value_ptr(model));
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m_vao.bind();
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glDrawElements(GL_TRIANGLES, m_index_count, GL_UNSIGNED_INT, nullptr);
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m_vao.unbind();
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m_prog.unuse();
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}
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auto sphere::build_mesh() -> void {
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struct vertex {
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glm::vec3 position;
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glm::vec3 normal;
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glm::vec2 uv;
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glm::vec3 color;
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};
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std::uint32_t const div = 32;
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std::vector<vertex> vertices;
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std::vector<std::uint32_t> indices;
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// Distinct colors for each cube face so seams are visible
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glm::vec3 const face_colors[6] = {
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{1.0f, 0.2f, 0.2f}, // +X red
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{0.2f, 1.0f, 0.2f}, // -X green
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{0.2f, 0.2f, 1.0f}, // +Y blue
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{1.0f, 1.0f, 0.2f}, // -Y yellow
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{1.0f, 0.2f, 1.0f}, // +Z magenta
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{0.2f, 1.0f, 1.0f}, // -Z cyan
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};
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// Generate 6 cube faces, each with div x div vertices
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auto add_face = [&](glm::vec3 const& center, glm::vec3 const& u_axis,
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glm::vec3 const& v_axis, std::uint32_t face_idx) -> void {
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for (std::uint32_t i = 0; i < div; ++i) {
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for (std::uint32_t j = 0; j < div; ++j) {
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float const s = float(i) / float(div - 1) * 2.0f - 1.0f;
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float const t = float(j) / float(div - 1) * 2.0f - 1.0f;
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// Position on cube face
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glm::vec3 pos = center + u_axis * s + v_axis * t;
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// FIX: normalize to project onto unit sphere
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// (the original nrz.cpp used a broken formula with p=50.0)
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float const len = glm::length(pos);
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glm::vec3 normal = pos / len;
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vertices.push_back({normal, normal, {float(i) / float(div - 1), float(j) / float(div - 1)}, face_colors[face_idx]});
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}
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}
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};
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// +X face (right)
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add_face(glm::vec3{1.0f, 0.0f, 0.0f}, glm::vec3{0.0f, 1.0f, 0.0f}, glm::vec3{0.0f, 0.0f, 1.0f}, 0);
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// -X face (left)
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add_face(glm::vec3{-1.0f, 0.0f, 0.0f}, glm::vec3{0.0f, 1.0f, 0.0f}, glm::vec3{0.0f, 0.0f, -1.0f}, 1);
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// +Y face (top)
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add_face(glm::vec3{0.0f, 1.0f, 0.0f}, glm::vec3{1.0f, 0.0f, 0.0f}, glm::vec3{0.0f, 0.0f, -1.0f}, 2);
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// -Y face (bottom)
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add_face(glm::vec3{0.0f, -1.0f, 0.0f}, glm::vec3{1.0f, 0.0f, 0.0f}, glm::vec3{0.0f, 0.0f, 1.0f}, 3);
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// +Z face (front)
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add_face(glm::vec3{0.0f, 0.0f, 1.0f}, glm::vec3{1.0f, 0.0f, 0.0f}, glm::vec3{0.0f, 1.0f, 0.0f}, 4);
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// -Z face (back)
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add_face(glm::vec3{0.0f, 0.0f, -1.0f}, glm::vec3{-1.0f, 0.0f, 0.0f}, glm::vec3{0.0f, 1.0f, 0.0f}, 5);
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// Generate indices for each face
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std::uint32_t offset = 0;
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for (std::uint32_t face = 0; face < 6; ++face) {
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for (std::uint32_t i = 0; i < div - 1; ++i) {
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for (std::uint32_t j = 0; j < div - 1; ++j) {
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std::uint32_t const a = offset + i * div + j;
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std::uint32_t const b = offset + (i + 1) * div + j;
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std::uint32_t const c = offset + (i + 1) * div + j + 1;
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std::uint32_t const d = offset + i * div + j + 1;
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// Two triangles per quad (consistent winding)
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indices.push_back(a);
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indices.push_back(b);
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indices.push_back(d);
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indices.push_back(b);
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indices.push_back(c);
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indices.push_back(d);
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}
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}
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offset += div * div;
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}
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m_index_count = static_cast<GLsizei>(indices.size());
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m_vbo.upload(vertices.data(), vertices.size() * sizeof(vertex));
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m_ebo.upload(indices.data(), indices.size() * sizeof(std::uint32_t));
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m_vao.bind();
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m_vbo.bind();
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m_ebo.bind();
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// location 0: position (vec3)
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glEnableVertexAttribArray(0);
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glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(vertex), nullptr);
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// location 1: normal (vec3)
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glEnableVertexAttribArray(1);
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glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(vertex),
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reinterpret_cast<void*>(3 * sizeof(float)));
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// location 2: uv (vec2)
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glEnableVertexAttribArray(2);
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glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(vertex),
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reinterpret_cast<void*>(6 * sizeof(float)));
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// location 3: color (vec3)
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glEnableVertexAttribArray(3);
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glVertexAttribPointer(3, 3, GL_FLOAT, GL_FALSE, sizeof(vertex),
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reinterpret_cast<void*>(8 * sizeof(float)));
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m_vao.unbind();
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m_vbo.unbind();
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m_ebo.unbind();
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}
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auto sphere::build_shader() -> bool {
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char const* vert_src = R"glsl(
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#version 410 core
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layout(location = 0) in vec3 a_pos;
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layout(location = 1) in vec3 a_normal;
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layout(location = 2) in vec2 a_uv;
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layout(location = 3) in vec3 a_color;
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uniform mat4 u_model;
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uniform mat4 u_view;
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uniform mat4 u_proj;
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out vec3 v_normal;
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out vec3 v_world_pos;
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out vec2 v_uv;
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out vec3 v_color;
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void main() {
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gl_Position = u_proj * u_view * u_model * vec4(a_pos, 1.0);
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v_normal = mat3(u_model) * a_normal;
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v_world_pos = (u_model * vec4(a_pos, 1.0)).xyz;
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v_uv = a_uv;
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v_color = a_color;
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}
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)glsl";
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char const* frag_src = R"glsl(
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#version 410 core
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in vec3 v_normal;
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in vec3 v_world_pos;
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in vec2 v_uv;
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in vec3 v_color;
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out vec4 frag_color;
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void main() {
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vec3 light_dir = normalize(vec3(1.0, 1.0, 2.0));
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vec3 normal = normalize(v_normal);
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float diff = max(dot(normal, light_dir), 0.0);
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vec3 ambient = vec3(0.2);
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vec3 result = (ambient + diff * 0.8) * v_color;
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frag_color = vec4(result, 1.0);
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}
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)glsl";
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if (!m_prog.compile_vertex(vert_src) || !m_prog.compile_fragment(frag_src) || !m_prog.link()) {
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return false;
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}
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m_loc_proj = glGetUniformLocation(m_prog.id(), "u_proj");
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m_loc_view = glGetUniformLocation(m_prog.id(), "u_view");
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m_loc_model = glGetUniformLocation(m_prog.id(), "u_model");
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return true;
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}
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}
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