duuqnd/cave-story-solaris
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Offload texture coord transformation to GPU

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I imagine this isn't too helpful when the GPU is the bottleneck, like
on my Raspberry Pi.
This commit is contained in:
Clownacy 2020-09-15 14:21:58 +01:00
parent f0e1119a91
commit 07e4e3b971
1 changed files with 30 additions and 10 deletions
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40
src/Backends/Rendering/OpenGL3.cpp
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@ -63,11 +63,19 @@ typedef struct VertexBufferSlot
static struct static struct
{ {
GLuint id; GLuint id;
struct
{
GLint texture_coordinate_transform;
} uniforms;
} program_texture; } program_texture;
static struct static struct
{ {
GLuint id; GLuint id;
struct
{
GLint texture_coordinate_transform;
} uniforms;
} program_texture_colour_key; } program_texture_colour_key;
static struct static struct
@ -84,6 +92,7 @@ static struct
GLuint id; GLuint id;
struct struct
{ {
GLint texture_coordinate_transform;
GLint colour; GLint colour;
} uniforms; } uniforms;
} program_glyph; } program_glyph;
@ -122,12 +131,13 @@ void main() \
static const GLchar *vertex_shader_texture = " \ static const GLchar *vertex_shader_texture = " \
#version 100\n \ #version 100\n \
uniform vec2 texture_coordinate_transform; \
attribute vec2 input_vertex_coordinates; \ attribute vec2 input_vertex_coordinates; \
attribute vec2 input_texture_coordinates; \ attribute vec2 input_texture_coordinates; \
varying vec2 texture_coordinates; \ varying vec2 texture_coordinates; \
void main() \ void main() \
{ \ { \
texture_coordinates = input_texture_coordinates; \ texture_coordinates = input_texture_coordinates * texture_coordinate_transform; \
gl_Position = vec4(input_vertex_coordinates.xy, 0.0, 1.0); \ gl_Position = vec4(input_vertex_coordinates.xy, 0.0, 1.0); \
} \ } \
"; ";
@ -192,12 +202,13 @@ void main() \
static const GLchar *vertex_shader_texture = " \ static const GLchar *vertex_shader_texture = " \
#version 150 core\n \ #version 150 core\n \
uniform vec2 texture_coordinate_transform; \
in vec2 input_vertex_coordinates; \ in vec2 input_vertex_coordinates; \
in vec2 input_texture_coordinates; \ in vec2 input_texture_coordinates; \
out vec2 texture_coordinates; \ out vec2 texture_coordinates; \
void main() \ void main() \
{ \ { \
texture_coordinates = input_texture_coordinates; \ texture_coordinates = input_texture_coordinates * texture_coordinate_transform; \
gl_Position = vec4(input_vertex_coordinates.xy, 0.0, 1.0); \ gl_Position = vec4(input_vertex_coordinates.xy, 0.0, 1.0); \
} \ } \
"; ";
@ -492,7 +503,13 @@ RenderBackend_Surface* RenderBackend_Init(const char *window_title, size_t scree
if (program_texture.id != 0 && program_texture_colour_key.id != 0 && program_colour_fill.id != 0 && program_glyph.id != 0) if (program_texture.id != 0 && program_texture_colour_key.id != 0 && program_colour_fill.id != 0 && program_glyph.id != 0)
{ {
// Get shader uniforms // Get shader uniforms
program_texture.uniforms.texture_coordinate_transform = glGetUniformLocation(program_texture.id, "texture_coordinate_transform");
program_texture_colour_key.uniforms.texture_coordinate_transform = glGetUniformLocation(program_texture_colour_key.id, "texture_coordinate_transform");
program_colour_fill.uniforms.colour = glGetUniformLocation(program_colour_fill.id, "colour"); program_colour_fill.uniforms.colour = glGetUniformLocation(program_colour_fill.id, "colour");
program_glyph.uniforms.texture_coordinate_transform = glGetUniformLocation(program_glyph.id, "texture_coordinate_transform");
program_glyph.uniforms.colour = glGetUniformLocation(program_glyph.id, "colour"); program_glyph.uniforms.colour = glGetUniformLocation(program_glyph.id, "colour");
// Set up framebuffer (used for surface-to-surface blitting) // Set up framebuffer (used for surface-to-surface blitting)
@ -571,6 +588,7 @@ void RenderBackend_DrawScreen(void)
last_destination_texture = 0; last_destination_texture = 0;
glUseProgram(program_texture.id); glUseProgram(program_texture.id);
glUniform2f(program_texture.uniforms.texture_coordinate_transform, 1.0f, 1.0f);
glDisable(GL_BLEND); glDisable(GL_BLEND);
@ -755,6 +773,7 @@ void RenderBackend_Blit(RenderBackend_Surface *source_surface, const RenderBacke
// Switch to colour-key shader if we have to // Switch to colour-key shader if we have to
glUseProgram(colour_key ? program_texture_colour_key.id : program_texture.id); glUseProgram(colour_key ? program_texture_colour_key.id : program_texture.id);
glUniform2f(colour_key ? program_texture_colour_key.uniforms.texture_coordinate_transform : program_texture.uniforms.texture_coordinate_transform, 1.0f / source_surface->width, 1.0f / source_surface->height);
glDisable(GL_BLEND); glDisable(GL_BLEND);
@ -788,10 +807,10 @@ void RenderBackend_Blit(RenderBackend_Surface *source_surface, const RenderBacke
vertex_buffer_slot->vertices[1][2].position.x = vertex_left; vertex_buffer_slot->vertices[1][2].position.x = vertex_left;
vertex_buffer_slot->vertices[1][2].position.y = vertex_bottom; vertex_buffer_slot->vertices[1][2].position.y = vertex_bottom;
const GLfloat texture_left = rect->left / (GLfloat)source_surface->width; const GLfloat texture_left = rect->left;
const GLfloat texture_top = rect->top / (GLfloat)source_surface->height; const GLfloat texture_top = rect->top;
const GLfloat texture_right = rect->right / (GLfloat)source_surface->width; const GLfloat texture_right = rect->right;
const GLfloat texture_bottom = rect->bottom / (GLfloat)source_surface->height; const GLfloat texture_bottom = rect->bottom;
vertex_buffer_slot->vertices[0][0].texture.x = texture_left; vertex_buffer_slot->vertices[0][0].texture.x = texture_left;
vertex_buffer_slot->vertices[0][0].texture.y = texture_top; vertex_buffer_slot->vertices[0][0].texture.y = texture_top;
@ -945,6 +964,7 @@ void RenderBackend_PrepareToDrawGlyphs(RenderBackend_GlyphAtlas *atlas, RenderBa
last_blue = blue; last_blue = blue;
glUseProgram(program_glyph.id); glUseProgram(program_glyph.id);
glUniform2f(program_glyph.uniforms.texture_coordinate_transform, 1.0f / atlas->width, 1.0f / atlas->height);
glUniform4f(program_glyph.uniforms.colour, red / 255.0f, green / 255.0f, blue / 255.0f, 1.0f); glUniform4f(program_glyph.uniforms.colour, red / 255.0f, green / 255.0f, blue / 255.0f, 1.0f);
// Point our framebuffer to the destination texture // Point our framebuffer to the destination texture
@ -986,10 +1006,10 @@ void RenderBackend_DrawGlyph(RenderBackend_GlyphAtlas *atlas, long x, long y, si
vertex_buffer_slot->vertices[1][2].position.x = vertex_left; vertex_buffer_slot->vertices[1][2].position.x = vertex_left;
vertex_buffer_slot->vertices[1][2].position.y = vertex_bottom; vertex_buffer_slot->vertices[1][2].position.y = vertex_bottom;
const GLfloat texture_left = glyph_x / (GLfloat)atlas->width; const GLfloat texture_left = glyph_x;
const GLfloat texture_top = glyph_y / (GLfloat)atlas->height; const GLfloat texture_top = glyph_y;
const GLfloat texture_right = (glyph_x + glyph_width) / (GLfloat)atlas->width; const GLfloat texture_right = glyph_x + glyph_width;
const GLfloat texture_bottom = (glyph_y + glyph_height) / (GLfloat)atlas->height; const GLfloat texture_bottom = glyph_y + glyph_height;
vertex_buffer_slot->vertices[0][0].texture.x = texture_left; vertex_buffer_slot->vertices[0][0].texture.x = texture_left;
vertex_buffer_slot->vertices[0][0].texture.y = texture_top; vertex_buffer_slot->vertices[0][0].texture.y = texture_top;